Improve package version constraint suggestions.

app/models/package_version.py

Index: app/models/package_version.py
diff --git a/app/models/package_version.py b/app/models/package_version.py
index b38891d74556aa6956fdce8c47dfa06a3aa14d35..c9160becc93c9b357917e4e1b6cefe45b5514ce8 100644
--- a/app/models/package_version.py
+++ b/app/models/package_version.py
@@ -244,11 +244,15 @@ class PackageVersion(db.Model):
     @property
     def example_version_constraint(self):
         """Return the example version constraint for this package."""
-        if self.version.in_initial_development:
-            return json.dumps(">=%s <%d.%d.0" %
-                (self.version, self.version.major, self.version.minor + 1))
-        return json.dumps(
-            ">=%s <%d.0.0" % (self.version, self.version.major + 1))
+        if not self.verison.is_prerelease:
+            return json.dumps("^%s" % self.version)
+
+        return json.dumps(">=%s <%d.%d.%d" % (
+            self.version,
+            self.version.major,
+            self.version.minor,
+            self.version.patch
+        ))

[kustermann, 2015/05/19 08:24:36]

I'm not sure if this is working as intended.

A while ago I filed http://dartbug.com/20404 which was marked as AsDesigned and
says basically:
  "0.0.3-dev" does not satisfy the constraint '>=0.0.3-dev <0.0.3'

=> Your change builds exactly such a constraint.


Now since pub defines it's *own semantics* of what constraints and the operators
<, <=, >, >= mean, and I'm not a pub expert, I don't know what to use. This
issue http://dartbug.com/20302 says:

  "<1.2.3"   No pre-release versions are considered
  "<=1.2.3"  Pre-release versions are considered

This might indicate that we could do:
 a)  ">=1.2.3-dev <=1.2.3"
 b)  ">=1.2.3-dev <=1.2.3-dev"

If option a) is not desired, because we don't want to include 1.2.3, then option
b) seems to be the only choice.


But you're much more familiar with pub's semantic versioning, so maybe I'm
misunderstanding something here?

 
     @property
     def storage_path(self):