Strings recipes for the Dart Cookbook

String recipes for the Dart Cookbook.


More tweaks


Tweaks and formatting changes


Tweaks. Removed print statements.


Added Unicode string output to examples


Added 2 more recipes about using regExps.

Finding regExp matches.
Subsitituting strings based on regExps.

Added 2 more recipes.

Changing string case.
Determining if a string contains another string.

Added 3 more recipes.

Getting the length of a string.
Splitting strings.
subscripting strings.

Wrote recipe for trimming whitespace from a string


Added recipe for testing whether a string is empty.


Added recipe for converting between characters and numbers.


Wrote incrementally building a string using StringBuffer recipe


Wrote interpolating expressions recipe


Finalized text of concatenating strings recipe.

Moved tests for concatenating strings into own file.
Cleaned up system for aggregating tests.

Added tests for string recipes.

concatenating strings
interpolating expressions
converting between string characters and numerical codes
determining if string is empty
trimming whitespace from a string
getting the length of a string
subscripting a string that contains symbols
splitting a string
changing the case of a string
determining whether a string contains a substring
finding occurrences of a string inside another string
substituting strings based on regExp matches

BUG=

[shailentuli, 2013-02-26 22:22:33]

This is the first draft of 13 Strings recipes for the Cookbook.

There's a ton of Unicode stuff in there. If you are new to Unicode or UTF-16, I
would recommend this talk:

http://www.youtube.com/watch?v=XD_5xDN7KUA

I think that it might be a good idea to preface the recipes with a short
introduction to how the Strings library works, what code units, code points,
surrogate pairs, etc. are. 

I have written the recipes assuming that these concepts are understood by the
reader. 

As always, thank you for taking the time to read this.

- Shailen

[shailentuli, 2013-02-26 22:22:57]

A staged version of the recipes can be read at:

https://github.com/dart-lang/cookbook/blob/strings/recipes/src/core/strings.md

[sethladd, 2013-02-26 23:11:54]

As you mentioned, there's a bit of background required. Differences between
codeUnit, a "character", a rune, string encodings, etc. I didn't find anything
that eased me into these topics. I don't think we should assume a developer
knows what those things are. Suggest a paragraph or two intro to this chapter
with some fundamentals. But maybe those fundamentals can be worded as recipes?

[sethladd, 2013-02-26 23:41:45]

Not finished, but thanks for doing this. It's going to be very useful.

https://chromiumcodereview.appspot.com/12335109/diff/4001/recipes/src/core/st...
File recipes/src/core/strings.md (right):

https://chromiumcodereview.appspot.com/12335109/diff/4001/recipes/src/core/st...
recipes/src/core/strings.md:5: You want to know how to concatenate strings in
Dart. You tried using `+`, but
A more concise way:

"You want to combine two or more strings"

Avoid "you want to know how to..."

https://chromiumcodereview.appspot.com/12335109/diff/4001/recipes/src/core/st...
recipes/src/core/strings.md:12: 'Dart'  'is' ' fun!'; // 'Dart is fun!'
assign to variable

https://chromiumcodereview.appspot.com/12335109/diff/4001/recipes/src/core/st...
recipes/src/core/strings.md:37: Use `concat()`:
I'm not sure we want to show things that we generally don't recommend. Why show
this and not show StringBuffer? Shouldn't it be the other way around?

https://chromiumcodereview.appspot.com/12335109/diff/4001/recipes/src/core/st...
recipes/src/core/strings.md:39: 'Dewey'.concat(' Cheatem').concat('
and').concat( ' Howe'); // 'Dewey Cheatem and Howe'
nice example :)

https://chromiumcodereview.appspot.com/12335109/diff/4001/recipes/src/core/st...
recipes/src/core/strings.md:60: You can put the value of an expression inside a
string by using ${expression}.
wrap in backticks?

https://chromiumcodereview.appspot.com/12335109/diff/4001/recipes/src/core/st...
recipes/src/core/strings.md:60: You can put the value of an expression inside a
string by using ${expression}.
Shouldn't it be more declarative?

s/You can put/Put the

I don't know what proper cookbook style is.

https://chromiumcodereview.appspot.com/12335109/diff/4001/recipes/src/core/st...
recipes/src/core/strings.md:82: You should consider implementing a `toString()`
method for user-defined
This is a separate recipe. Consider breaking it out to a Problem: "How to
control the output of an object in string interpolation"

https://chromiumcodereview.appspot.com/12335109/diff/4001/recipes/src/core/st...
recipes/src/core/strings.md:91: 'Point: $point'; // "Point: Instance of 'Point'"
assign to variable. Creating objects without variables is jarring to me.

https://chromiumcodereview.appspot.com/12335109/diff/4001/recipes/src/core/st...
recipes/src/core/strings.md:106: r'$favFood'; // '$favFood'
This came out of left field. Can you add a recipe for "How do I use special
characters in my string that would otherwise be interpreted?" before this?

https://chromiumcodereview.appspot.com/12335109/diff/4001/recipes/src/core/st...
recipes/src/core/strings.md:126: 
assign to variable

https://chromiumcodereview.appspot.com/12335109/diff/4001/recipes/src/core/st...
recipes/src/core/strings.md:131: (`writeCharCode()`), write with an added
newline ('writeln()`), and more. Here
Is this now writeCharUnit?

https://chromiumcodereview.appspot.com/12335109/diff/4001/recipes/src/core/st...
recipes/src/core/strings.md:145: ## Converting between string characters and
numbers
Can you change the title? I saw "numbers" and I thought you meant like toInt()

[Cutch, 2013-02-26 23:57:18]

In the introduction, you might want to say something like:

A rune/code point map to character displayed on the screen.
A rune/code point are made up of tuples (1 or more) of code units. 
A code unit is a 16-bit integer.

Ignoring that some runes/code points are not displayable: Thoughts?

[shailentuli, 2013-03-07 03:35:33]

I have just pushed a comprehensive rewrite of the string recipes for the
Cookbook.  

You can read a staged version at:
https://github.com/dart-lang/cookbook/blob/strings/recipes/src/core/strings.md

I would recommend reading each recipe in parallel with the corresponding test
file.  Test files for string recipes can be found in recipes/test/core/strings.

As always, your feedback is greatly appreciated.

[sethladd, 2013-03-07 05:15:15]

https://chromiumcodereview.appspot.com/12335109/diff/9001/recipes/src/core/st...
File recipes/src/core/strings.md (right):

https://chromiumcodereview.appspot.com/12335109/diff/9001/recipes/src/core/st...
recipes/src/core/strings.md:121: You want to create strings that contain Dart
expressions and identifiers.
This sounds like I already know what the solution is. Can you reword this to
sound like someone asking who doesn't know what dart is?

https://chromiumcodereview.appspot.com/12335109/diff/9001/recipes/src/core/st...
recipes/src/core/strings.md:170: ## Escaping special characters
Is this the right usage of the terminology? This is not how I think of escaping.
The problem here is vague and the solution doesn't look like escaping... I would
think the problem would be "how do I insert a newline character?" with the
solution you use here.

https://chromiumcodereview.appspot.com/12335109/diff/9001/recipes/src/core/st...
recipes/src/core/strings.md:218: var sb = new StringBuffer();
This example doesn't show off the right way to use a string buffer, because what
you have here could easily be written with adjacent string literals. How about a
for loop that builds a string?

https://chromiumcodereview.appspot.com/12335109/diff/9001/recipes/src/core/st...
recipes/src/core/strings.md:247: You want to convert string characters into
numerical codes and back.
Is there a more real-life problem here? Why would I want to do this ever?

https://chromiumcodereview.appspot.com/12335109/diff/9001/recipes/src/core/st...
recipes/src/core/strings.md:329: You want to know if a string is empty. You
tried ` if(string) {...}`, but that
This is a great problem, well worded!

https://chromiumcodereview.appspot.com/12335109/diff/9001/recipes/src/core/st...
recipes/src/core/strings.md:490: You want to split a string into substrings.
can you add "based on some pattern". An example helps here.

[floitsch, 2013-03-07 17:22:06]

first round of comments.

https://chromiumcodereview.appspot.com/12335109/diff/9001/recipes/src/core/st...
File recipes/src/core/strings.md (right):

https://chromiumcodereview.appspot.com/12335109/diff/9001/recipes/src/core/st...
recipes/src/core/strings.md:13: The first plane (code points U+0000 to U+FFFF)
contains the most
should we stick to "rune" (here and in the rest)?
It is basically the first thing we explain in the section.

https://chromiumcodereview.appspot.com/12335109/diff/9001/recipes/src/core/st...
recipes/src/core/strings.md:36: numerically the same as code unit for that
charcter.
as *the* code unit for that char*a*cter.

https://chromiumcodereview.appspot.com/12335109/diff/9001/recipes/src/core/st...
recipes/src/core/strings.md:51: unit; non-BMP characters map 2 code units.
map to

https://chromiumcodereview.appspot.com/12335109/diff/9001/recipes/src/core/st...
recipes/src/core/strings.md:143: It is equivalent to the following:
I'm not sure we should call it "equivalent". It should be more efficient.

https://chromiumcodereview.appspot.com/12335109/diff/9001/recipes/src/core/st...
recipes/src/core/strings.md:195: If you prefer, you can use `\x` or `\u`
notation to indicate the special
We also have \u{A}

https://chromiumcodereview.appspot.com/12335109/diff/9001/recipes/src/core/st...
recipes/src/core/strings.md:267: Notice that using `runes` and `codeUnits()`
produces identical results
no () for codeUnits

https://chromiumcodereview.appspot.com/12335109/diff/9001/recipes/src/core/st...
recipes/src/core/strings.md:275: character using `codeUnits()` and `runes`
produces the following result:
no "()".

https://chromiumcodereview.appspot.com/12335109/diff/9001/recipes/src/core/st...
recipes/src/core/strings.md:334: Use `string.isEmpty`:
or just string == "". Both are fine.

https://chromiumcodereview.appspot.com/12335109/diff/9001/recipes/src/core/st...
recipes/src/core/strings.md:403: For characters that fit into 16 bites, the code
unit length is the same as the
bits

https://chromiumcodereview.appspot.com/12335109/diff/9001/recipes/src/core/st...
recipes/src/core/strings.md:422: want the number of distinct characters.
But what is a "character" ?
For example "é" is not necessarily just one rune...

https://chromiumcodereview.appspot.com/12335109/diff/9001/recipes/src/core/st...
recipes/src/core/strings.md:465: var charList = "Dart".runes.map((rune) =>
'*${new String.fromCharCode(rune)}*').toList();
I'm questioning the utility of these strings. "é" could be decomposed into two
runes. One string would be an "e" the other the combining accent.

https://chromiumcodereview.appspot.com/12335109/diff/9001/recipes/src/core/st...
recipes/src/core/strings.md:471: If you are sure that the string is in the Basic
Multilingual Plane (BMP), you
But then you can also just index into the string.

https://chromiumcodereview.appspot.com/12335109/diff/9001/recipes/src/core/st...
recipes/src/core/strings.md:530: Use `string.toUpperCase()` and
`string.toLowerCase()` to covert a string to
convert

https://chromiumcodereview.appspot.com/12335109/diff/9001/recipes/src/core/st...
recipes/src/core/strings.md:531: lower-case or upper-case, respectively:
No. this is not a good solution.
This only works in some languages, but not in all. A good solution is much more
complex.
The discussion only touches parts of the problem.

[erikcorry, 2013-03-07 18:26:51]

I have only glanced at it, but my first impression is that it starts out with
the bad news.  I think it would be great to start with the good news and the
basics, instead of immediately launching into the dark corners of UTF-16:

* Dart strings support the full Unicode range.
* All encoding and decoding is done by the browser or IO library, so you don't
have to deal with UTF-16, Latin 1, KOI-8 etc.
* Dart strings are immutable and the indexing operation gives you one-character
strings, since there is no separate char type
* If you want to get at the numeric values of the characters, here are the
constructors and iterators.

Once you have done that you can start talking about code units and runes and the
subtle difference between them.  Maybe worth mentioning that Java has the same
issues, but the core library does not provide nice rune-based operations?

Remember that even without surrogate pairs you can cover every single alphabetic
system in use in the whole world.  Up until 2010 you could also write every
single Kanji on the compulsory school list
(http://blogs.adobe.com/typblography/2010/12/joyo-kanji-revision.html) and also
every official name in Japan (in 2010 they added one non-basic-plane kanji to
the list :-( )

[Alan Knight, 2013-03-07 21:15:00]

https://chromiumcodereview.appspot.com/12335109/diff/9001/recipes/src/core/st...
File recipes/src/core/strings.md (right):

https://chromiumcodereview.appspot.com/12335109/diff/9001/recipes/src/core/st...
recipes/src/core/strings.md:3: Dart string represents a sequence of characters
encoded in UTF-16. Decoding
*A* Dart string

https://chromiumcodereview.appspot.com/12335109/diff/9001/recipes/src/core/st...
recipes/src/core/strings.md:9: 
I agree with Erik's comments that this is not what you want to start with. I'd
probably start with "I want to construct strings that have dynamic content" :
answer interpolation, and then go into concatenation, stringbuffers, escaping,
etc. I think it's important to put the preferred answer first, as people reading
the doc are likely to stop once they see one answer that does what they want.
I'd say mention at the beginning that they are UTF-16 and refer to a later
section on Unicode and runes.

Also, right now there are multiple different sections that deal with the issues
around codeUnits versus runes. I think all of that discussion should be grouped
together.

https://chromiumcodereview.appspot.com/12335109/diff/9001/recipes/src/core/st...
recipes/src/core/strings.md:60: so there's no great overhead in doing things
right.
This seems confusing. Dealing with Unicode is not the same as dealing with
non-UTF-16 characters. I'm not entirely convinced about the second sentence, but
I do think that most people can ignore the UTF-16 issues most of the time and
get by fine, even when they deal with non-BMP data. It's really only if you
split the data out and need to deal with it as semantic characters that it's a
problem, and even then you run would still into normalization issues that
Florian refers to with e-accent-aigu.

https://chromiumcodereview.appspot.com/12335109/diff/9001/recipes/src/core/st...
recipes/src/core/strings.md:175: 
Better phrased in terms of the problem. e.g. You want to put newlines, dollar
signs, or other special characters in your strings.

https://chromiumcodereview.appspot.com/12335109/diff/9001/recipes/src/core/st...
recipes/src/core/strings.md:194: 
Also \$.  And I don't see any mention of raw strings here.

https://chromiumcodereview.appspot.com/12335109/diff/9001/recipes/src/core/st...
recipes/src/core/strings.md:247: You want to convert string characters into
numerical codes and back.
On 2013/03/07 05:15:16, sethladd wrote:
> Is there a more real-life problem here? Why would I want to do this ever?

I need to compare character in a string to numerical values coming from another
source. Or I need to split a string up into individual characters, or operate on
the individual characters. If the semantics of the characters are important, and
the set isn't known to be restricted, then I need to do it in terms of runes.

https://chromiumcodereview.appspot.com/12335109/diff/9001/recipes/src/core/st...
recipes/src/core/strings.md:299: strings.
It's worth pointing out that this is always the case. Half of a surrogate pair
can never be mistaken for a single valid character.

https://chromiumcodereview.appspot.com/12335109/diff/9001/recipes/src/core/st...
recipes/src/core/strings.md:305: `String.fromCharCodes(charCodes)`:
I think it's important to point out that you can give it either runes or code
units and it can tell the difference and do the right thing automatically.

https://chromiumcodereview.appspot.com/12335109/diff/9001/recipes/src/core/st...
recipes/src/core/strings.md:348: be false.
And you will see a warning in the editor if you use an "if" statement with a
non-boolean

https://chromiumcodereview.appspot.com/12335109/diff/9001/recipes/src/core/st...
recipes/src/core/strings.md:358: emptyString == '\u2004'; // false
Are you saying that the string '\u0020' is supposed to be considered empty? I
wouldn't have thought so, and it doesn't appear to work that way if I test it. I
don't see why emptyString == anotherString wouldn't work. But I also don't see
why you'd want to do that instead of anotherString.isEmpty

https://chromiumcodereview.appspot.com/12335109/diff/9001/recipes/src/core/st...
recipes/src/core/strings.md:376: you can always use regExps.
This seems unclear. I think you mean "to remove *just* leading or *just*
trailing whitespace. As written it sounds like it's contradicting the lines
immediately previous.

https://chromiumcodereview.appspot.com/12335109/diff/9001/recipes/src/core/st...
recipes/src/core/strings.md:385: 
Or you could do this with the runes or codePoints, but RegExp is likely a good
bit more efficient.

https://chromiumcodereview.appspot.com/12335109/diff/9001/recipes/src/core/st...
recipes/src/core/strings.md:422: want the number of distinct characters.
On 2013/03/07 17:22:07, floitsch wrote:
> But what is a "character" ?
> For example "é" is not necessarily just one rune...

Yes, we probably need yet another section on these, and a reference from here

https://chromiumcodereview.appspot.com/12335109/diff/9001/recipes/src/core/st...
recipes/src/core/strings.md:439: 
Technically I think that's "Teacup without handle". Which is a shame, the idea
of a unicode character for coffee is very appealing.

https://chromiumcodereview.appspot.com/12335109/diff/9001/recipes/src/core/st...
recipes/src/core/strings.md:453: 
I think the recommended answer is that you just use indexing, with a caveat that
if you have non-BMP characters and that's what you're worried about then you
need to work in terms of runes or split the string up into individual
characters. For the great majority of uses simple indexing will be fine, even if
there are non-BMP characters.

https://chromiumcodereview.appspot.com/12335109/diff/9001/recipes/src/core/st...
recipes/src/core/strings.md:558: ## Determining whether a string contains
another string
These should be much earlier, as they seem like very common tasks.

https://chromiumcodereview.appspot.com/12335109/diff/9001/recipes/src/core/st...
recipes/src/core/strings.md:654: // 'I like IKE but I ♡ LUCY'
I think it would be nice to see some discussion of some the things people might
not be expecting to see that could be quite useful, e.g. Iterable.join and
splitMapJoin.

[shailentuli, 2013-03-08 22:38:26]

Thank you all very much for your comments.

This patch deals with minor issues brought up in your comments. More substantial
issues will be addressed in another patch.

1) I agree with Erik and Alan that the Chapter needs a proper introduction to
the String library. I will write that.  

2) While structuring the recipes, I've tried to first present a solution that
works across all of Unicode, and then present an alternative that will work
"most of the time."  I am not sure how I feel about this approach: perhaps, we
should only be presenting solutions that always work and stay away from
recommending things that work only for BMP strings.  Can you offer your
thoughts? 

3) In keeping with 2), above, I have tried to present 3 types of examples that
use 1) only ASCII or Latin1 characters, 2) non-ASCII and non-Latin1 BMP
characters, and 3) non-BMP characters.

I am a little stuck finding *realistic* examples using non-BMP characters. I'm
avoiding using examples from exotic sources (Linear-B, Byzantine Musical
Symbols, etc) because I don't want most developers to conclude that since they
would never use these things, they don't have to worry about non-BMP strings.   

Can you recommend good non-BMP examples?

3) Can you define the term "character" for me?  I'm trying hard not to overload
the term sloppily, and would like to know precisely what we mean by that term.

Again, many thanks for all your comments. They are much appreciated.

https://chromiumcodereview.appspot.com/12335109/diff/9001/recipes/src/core/st...
File recipes/src/core/strings.md (right):

https://chromiumcodereview.appspot.com/12335109/diff/9001/recipes/src/core/st...
recipes/src/core/strings.md:3: Dart string represents a sequence of characters
encoded in UTF-16. Decoding
On 2013/03/07 21:15:00, Alan Knight wrote:
> *A* Dart string

Done.

https://chromiumcodereview.appspot.com/12335109/diff/9001/recipes/src/core/st...
recipes/src/core/strings.md:36: numerically the same as code unit for that
charcter.
On 2013/03/07 17:22:07, floitsch wrote:
> as *the* code unit for that char*a*cter.

Done.

https://chromiumcodereview.appspot.com/12335109/diff/9001/recipes/src/core/st...
recipes/src/core/strings.md:51: unit; non-BMP characters map 2 code units.
On 2013/03/07 17:22:07, floitsch wrote:
> map to

Done.

https://chromiumcodereview.appspot.com/12335109/diff/9001/recipes/src/core/st...
recipes/src/core/strings.md:60: so there's no great overhead in doing things
right.
On 2013/03/07 21:15:00, Alan Knight wrote:
> This seems confusing. Dealing with Unicode is not the same as dealing with
> non-UTF-16 characters. I'm not entirely convinced about the second sentence,
but
> I do think that most people can ignore the UTF-16 issues most of the time and
> get by fine, even when they deal with non-BMP data. It's really only if you
> split the data out and need to deal with it as semantic characters that it's a
> problem, and even then you run would still into normalization issues that
> Florian refers to with e-accent-aigu.

You are quite right. I am removing this section. When I write a full
introduction to begin this chapter, I will include some of these issues there.

https://chromiumcodereview.appspot.com/12335109/diff/9001/recipes/src/core/st...
recipes/src/core/strings.md:170: ## Escaping special characters
On 2013/03/07 05:15:16, sethladd wrote:
> Is this the right usage of the terminology? This is not how I think of
escaping.
> The problem here is vague and the solution doesn't look like escaping... I
would
> think the problem would be "how do I insert a newline character?" with the
> solution you use here.

I've used Alan's recommendation below.

https://chromiumcodereview.appspot.com/12335109/diff/9001/recipes/src/core/st...
recipes/src/core/strings.md:175: 
On 2013/03/07 21:15:00, Alan Knight wrote:
> Better phrased in terms of the problem. e.g. You want to put newlines, dollar
> signs, or other special characters in your strings.

Done.

https://chromiumcodereview.appspot.com/12335109/diff/9001/recipes/src/core/st...
recipes/src/core/strings.md:194: 
On 2013/03/07 21:15:00, Alan Knight wrote:
> Also \$.  And I don't see any mention of raw strings here.

I'm saving them for a separate recipe which will follow this one.

https://chromiumcodereview.appspot.com/12335109/diff/9001/recipes/src/core/st...
recipes/src/core/strings.md:195: If you prefer, you can use `\x` or `\u`
notation to indicate the special
On 2013/03/07 17:22:07, floitsch wrote:
> We also have \u{A}

I've added an example of this.

https://chromiumcodereview.appspot.com/12335109/diff/9001/recipes/src/core/st...
recipes/src/core/strings.md:267: Notice that using `runes` and `codeUnits()`
produces identical results
On 2013/03/07 17:22:07, floitsch wrote:
> no () for codeUnits

Done.

https://chromiumcodereview.appspot.com/12335109/diff/9001/recipes/src/core/st...
recipes/src/core/strings.md:275: character using `codeUnits()` and `runes`
produces the following result:
On 2013/03/07 17:22:07, floitsch wrote:
> no "()".

Done.

https://chromiumcodereview.appspot.com/12335109/diff/9001/recipes/src/core/st...
recipes/src/core/strings.md:358: emptyString == '\u2004'; // false
On 2013/03/07 21:15:00, Alan Knight wrote:
> Are you saying that the string '\u0020' is supposed to be considered empty? I
> wouldn't have thought so, and it doesn't appear to work that way if I test it.
I
> don't see why emptyString == anotherString wouldn't work. But I also don't see
> why you'd want to do that instead of anotherString.isEmpty

This was erroneously added here. Removed.

https://chromiumcodereview.appspot.com/12335109/diff/9001/recipes/src/core/st...
recipes/src/core/strings.md:376: you can always use regExps.
On 2013/03/07 21:15:00, Alan Knight wrote:
> This seems unclear. I think you mean "to remove *just* leading or *just*
> trailing whitespace. As written it sounds like it's contradicting the lines
> immediately previous.

Done.

https://chromiumcodereview.appspot.com/12335109/diff/9001/recipes/src/core/st...
recipes/src/core/strings.md:403: For characters that fit into 16 bites, the code
unit length is the same as the
On 2013/03/07 17:22:07, floitsch wrote:
> bits

Done.

https://chromiumcodereview.appspot.com/12335109/diff/9001/recipes/src/core/st...
recipes/src/core/strings.md:422: want the number of distinct characters.
On 2013/03/07 17:22:07, floitsch wrote:
> But what is a "character" ?
> For example "é" is not necessarily just one rune...

Changing to runes.

https://chromiumcodereview.appspot.com/12335109/diff/9001/recipes/src/core/st...
recipes/src/core/strings.md:439: 
On 2013/03/07 21:15:00, Alan Knight wrote:
> Technically I think that's "Teacup without handle". Which is a shame, the idea
> of a unicode character for coffee is very appealing.

You are quite correct. Renaming to teacup.

https://chromiumcodereview.appspot.com/12335109/diff/9001/recipes/src/core/st...
recipes/src/core/strings.md:530: Use `string.toUpperCase()` and
`string.toLowerCase()` to covert a string to
On 2013/03/07 17:22:07, floitsch wrote:
> convert

Done.

https://chromiumcodereview.appspot.com/12335109/diff/9001/recipes/src/core/st...
recipes/src/core/strings.md:531: lower-case or upper-case, respectively:
On 2013/03/07 17:22:07, floitsch wrote:
> No. this is not a good solution.
> This only works in some languages, but not in all. A good solution is much
more
> complex.
> The discussion only touches parts of the problem.

Agreed. The goal is to show people how to correctly use string.toUpperCase() and
string.toLowerCase(). In the context of that, what specifically would you like
included in the discussion?

[floitsch, 2013-03-09 00:01:41]

DBC.
I'm also missing raw strings.

https://chromiumcodereview.appspot.com/12335109/diff/9001/recipes/src/core/st...
File recipes/src/core/strings.md (right):

https://chromiumcodereview.appspot.com/12335109/diff/9001/recipes/src/core/st...
recipes/src/core/strings.md:531: lower-case or upper-case, respectively:
On 2013/03/08 22:38:26, shailentuli wrote:
> On 2013/03/07 17:22:07, floitsch wrote:
> > No. this is not a good solution.
> > This only works in some languages, but not in all. A good solution is much
> more
> > complex.
> > The discussion only touches parts of the problem.
> 
> Agreed. The goal is to show people how to correctly use string.toUpperCase()
and
> string.toLowerCase(). In the context of that, what specifically would you like
> included in the discussion?

Well, that it doesn't work except in some languages.
For example in turkish it fails:
http://stackoverflow.com/questions/1850232/turkish-case-conversion-in-javascript

Ideally we wouldn't have a toUpperCase and toLowerCase on String, but there were
too many requests to add it.

https://chromiumcodereview.appspot.com/12335109/diff/17001/recipes/src/core/s...
File recipes/src/core/strings.md (right):

https://chromiumcodereview.appspot.com/12335109/diff/17001/recipes/src/core/s...
recipes/src/core/strings.md:99: You can also use the `concat()` method on a
string to concatenate it to another
I just gave an LGTM to Lasse for changing concat to String.+.
So you might want to wait for that to be committed and adapt this section.

https://chromiumcodereview.appspot.com/12335109/diff/17001/recipes/src/core/s...
recipes/src/core/strings.md:143: It is equivalent to the following:
It is not. the concat will make two copies, whereas the string-interpolation
only copies into the result.
The result is equivalent, though.

https://chromiumcodereview.appspot.com/12335109/diff/17001/recipes/src/core/s...
recipes/src/core/strings.md:422: want the number of runes.
You could add, that Twitter uses runes for the length limit.

https://chromiumcodereview.appspot.com/12335109/diff/17001/recipes/src/core/s...
recipes/src/core/strings.md:436: teacup.runes.toList()[0]; // 127861
If you want to access it only once, you can also use 'elementAt()'
teacup.runes.first is also valid here.

Furthermore note that runes has a special iterator that allows to move forward
and backward.

[Lasse Reichstein Nielsen, 2013-03-12 11:29:37]

https://codereview.chromium.org/12335109/diff/17001/recipes/test/core/strings...
File recipes/test/core/strings/concatenating_strings_test.dart (right):

https://codereview.chromium.org/12335109/diff/17001/recipes/test/core/strings...
recipes/test/core/strings/concatenating_strings_test.dart:40: test(': concat()',
() {
We're renaming concat to operator+.