Changes between Initial Version and Version 1 of RefactoringSteps/EliminateVariable

Timestamp:

Feb 18, 2012, 3:46:19 PM (13 years ago)

Author:

manualwiki

Comment:

--

RefactoringSteps/EliminateVariable

@@ +1 @@
+= Eliminate variable =
+
+In this refactoring, all instances of a variable are replaced with its bound value. Those instances of the variable where the value of the instance is not used can be dropped.
+
+Replacing all instances of variable {{{Y}}} with its value:
+
+{{{
+func(X) ->
+   Y=X+2,
+   Pid ! {value,Y},
+   Y.
+}}}
+
+Result:
+
+{{{
+func(X) ->
+
+   Pid ! {value,X+2},
+   X+2.
+}}}
+
+== Side conditions ==
+
+ * The variable has exactly one binding occurrence on the left hand side of a pattern matching expression, and not a part of a compound pattern.
+ 
+ * The expression bound to the variable has no side effects.
+
+ * Every variable of the expression is visible (that is, not shadowed) at every occurrence of the variable to be eliminated.
+
+ * If the selection is not specify a variable but it is inside a function clause, the tool gives a list to the user to select a variable. The list contains the reachable variables in the given function clause.
+
+
+== Transformation steps and compensations ==
+
+ 1. Every occurrence of the variable is substituted with the expression bound to it at its binding occurrence, with parentheses around the.
+
+ 2. If the result of the match expression that binds the variable is discarded, the whole match expression is removed. Otherwise, the match expression is replaced with its right hand side.