Avoid ivar name collisions

README.md

@@ -62,9 +62,12 @@ def fetch_aggregate_data
 end
 ```
 
-By default, Michie prepends `__michie_` to the method name to generate the
-instance variable name. This can be changed by passing a `prefix` option to
-`memoize` (see specs for details).
+By default, Michie generates an instance variable name prefix combining a
+"base" string `__michie_` with either an `m_` (normal methods), `b_` (bang
+methods ending in `!`) or `q_` (query methods ending in `?`). This prefix is
+combined with the method name of the method to be memoized to generate the
+instance variable name.  The base prefix can be changed by passing a `prefix`
+option to `memoize` (see specs for details).
 
 Since Michie uses the presence of an instance variable to signal memoization,
 `false` and `nil` values can be memoized (unlike techniques which use `||=`).

lib/michie.rb

@@ -73,13 +73,15 @@ def initialize(*, &block)
 
   module Helpers
     def ivar_name(method_name, memoization_prefix)
-      string = "#{memoization_prefix}_#{method_name.to_s}"
+      string = String === method_name ? method_name.dup : method_name.to_s
+      method_type_prefix = "m"
 
-      if string.end_with?("?", "!")
-        string = string.dup
-        string.sub!(/\?\Z/, "_query") || string.sub!(/!\Z/, "_bang")
+      if string.chomp!("?")
+        method_type_prefix = "q"
+      elsif string.chomp!("!")
+        method_type_prefix = "b"
       end
-      "@#{string}"
+      "@#{memoization_prefix}_#{method_type_prefix}_#{string}"
     end
     module_function :ivar_name
   end

spec/michie_spec.rb

@@ -26,7 +26,7 @@ def my_method
       expect(foo.my_method).to eq("result")
     end
 
-    expect(foo.instance_variables).to eq([:"@__michie_my_method"])
+    expect(foo.instance_variables).to eq([:"@__michie_m_my_method"])
   end
 
   it "memoizes methods passed as args" do
@@ -47,12 +47,12 @@ def method2
 
     expect(Listener).to receive(:call).once.and_return("result")
     2.times { expect(foo.method1).to eq("result") }
-    expect(foo.instance_variables).to eq([:"@__michie_method1"])
+    expect(foo.instance_variables).to eq([:"@__michie_m_method1"])
 
     expect(OtherListener).to receive(:call).once.and_return("result")
     2.times { expect(foo.method2).to eq("result") }
     expect(foo.instance_variables).to match_array(
-      [:"@__michie_method1", :"@__michie_method2"]
+      [:"@__michie_m_method1", :"@__michie_m_method2"]
     )
   end
 
@@ -127,9 +127,9 @@ def my_method?
     foo.my_method?
 
     expect(foo.instance_variables).to match_array([
-      :"@__michie_my_method",
-      :"@__michie_my_method_bang",
-      :"@__michie_my_method_query"
+      :"@__michie_m_my_method",
+      :"@__michie_b_my_method",
+      :"@__michie_q_my_method"
     ])
   end
 
@@ -146,7 +146,7 @@ def my_method
     foo = klass.new
     foo.my_method
 
-    expect(foo.instance_variables).to eq([:"@foo_my_method"])
+    expect(foo.instance_variables).to eq([:"@foo_m_my_method"])
   end
 
   it "maintains visibility of memoized methods" do