Allow external operator use

[tophsic]

Allowing to implement specific operators using Ruler API and store them in a specific namespace. Implementation can surely be improved.

Maybe I didn't undersand well how to bring my porcelain :)

[bobthecow]

I've been thinking a bit about extensibility, but this isn't exactly the direction I'd take. One question first: are you using PHP 5.4+?

(The way I word my suggestion depends on this answer :))

[tophsic]

For my personal use, I surely answer yes but unfortunately, I also have a job where we always use PHP 5.3 :)

[devantoine]

I personally love this pull request and find it so useful.

Nowadays there's no way to easily add operators without forking the project, and that's a real problem.

[bobthecow]

@tophsic I've cherry-picked this change into a branch made from the current develop:

develop...feature/external-operators

Aside from updating it to match the new class structure and constructor arguments, the one big change I made is that operator namespaces are registered on the RuleBuilder instance, rather than being registered statically on the Variable class.

As a test, I removed all the operator methods from RuleBuilder\Variable and all tests pass:

https://gist.github.com/bobthecow/30e7b9c83897a5f3f30d

Note that for this test I had to make a bunch of operator class aliases so that methods would work as expected (Multiplication -> Multiply, etc).

I'm not completely sold on this implementation, but I think it might be workable.

@jwage @ludicruz @devantoine what do you think?

[bobthecow]

And a bonus thing:

With a fairly simple change:

diff --git a/src/Ruler/Operator/Brevity/Eq.php b/src/Ruler/Operator/Brevity/Eq.php
new file mode 100644
index 0000000..b1aba02
--- /dev/null
+++ b/src/Ruler/Operator/Brevity/Eq.php
@@ -0,0 +1,9 @@
+<?php
+
+namespace Ruler\Operator\Brevity;
+
+use Ruler\Operator\EqualTo;
+
+class Eq extends EqualTo
+{
+}
diff --git a/src/Ruler/Operator/Brevity/Gt.php b/src/Ruler/Operator/Brevity/Gt.php
new file mode 100644
index 0000000..69981c7
--- /dev/null
+++ b/src/Ruler/Operator/Brevity/Gt.php
@@ -0,0 +1,9 @@
+<?php
+
+namespace Ruler\Operator\Brevity;
+
+use Ruler\Operator\GreaterThan;
+
+class Gt extends GreaterThan
+{
+}
diff --git a/src/Ruler/Operator/Brevity/Gte.php b/src/Ruler/Operator/Brevity/Gte.php
new file mode 100644
index 0000000..dadba9f
--- /dev/null
+++ b/src/Ruler/Operator/Brevity/Gte.php
@@ -0,0 +1,9 @@
+<?php
+
+namespace Ruler\Operator\Brevity;
+
+use Ruler\Operator\GreaterThanOrEqualTo;
+
+class Gte extends GreaterThanOrEqualTo
+{
+}
diff --git a/src/Ruler/Operator/Brevity/Lt.php b/src/Ruler/Operator/Brevity/Lt.php
new file mode 100644
index 0000000..aaa02e2
--- /dev/null
+++ b/src/Ruler/Operator/Brevity/Lt.php
@@ -0,0 +1,9 @@
+<?php
+
+namespace Ruler\Operator\Brevity;
+
+use Ruler\Operator\LessThan;
+
+class Lt extends LessThan
+{
+}
diff --git a/src/Ruler/Operator/Brevity/Lte.php b/src/Ruler/Operator/Brevity/Lte.php
new file mode 100644
index 0000000..74e0d41
--- /dev/null
+++ b/src/Ruler/Operator/Brevity/Lte.php
@@ -0,0 +1,9 @@
+<?php
+
+namespace Ruler\Operator\Brevity;
+
+use Ruler\Operator\LessThanOrEqualTo;
+
+class Lte extends LessThanOrEqualTo
+{
+}
diff --git a/src/Ruler/Operator/Brevity/Neq.php b/src/Ruler/Operator/Brevity/Neq.php
new file mode 100644
index 0000000..a1d937d
--- /dev/null
+++ b/src/Ruler/Operator/Brevity/Neq.php
@@ -0,0 +1,9 @@
+<?php
+
+namespace Ruler\Operator\Brevity;
+
+use Ruler\Operator\NotEqualTo;
+
+class Neq extends NotEqualTo
+{
+}

[bobthecow]

Closing this in favor of #30