[ruby-core:78052] [Ruby trunk Feature#12906] do/end blocks work with ensure/rescue/else
From:
shevegen@...
Date:
2016-11-08 14:57:53 UTC
List:
ruby-core #78052
Issue #12906 has been updated by Robert A. Heiler.
I like the idea. It would get rid of one begin/end clause if I understood
it correctly and be on the same level as class C/rescue/end definitions.
----------------------------------------
Feature #12906: do/end blocks work with ensure/rescue/else
https://bugs.ruby-lang.org/issues/12906#change-61405
* Author: Josh Cheek
* Status: Assigned
* Priority: Normal
* Assignee: Yukihiro Matsumoto
----------------------------------------
When you want to rescue in a block, you must do this:
~~~ruby
lambda do
begin
raise 'err'
rescue
$! # => #<RuntimeError: err>
end
end.call
~~~
I've wished on numerous occasions that I could omit the begin/end and not need the extra wrapper:
~~~ruby
lambda do
raise 'err'
rescue
$! # => #<RuntimeError: err>
end.call
~~~
This would be consistent with how classes and methods work:
~~~ruby
class C
raise 'err'
rescue
$! # => #<RuntimeError: err>
end
send def m
raise 'err'
rescue
$! # => #<RuntimeError: err>
end
~~~
It's not really clear to me how to submit this since it may require some discussion, but this is the diff:
~~~diff
diff --git a/parse.y b/parse.y
index 54ccc52..223e5d3 100644
--- a/parse.y
+++ b/parse.y
@@ -3757,7 +3757,7 @@ brace_body : {$<vars>$ = dyna_push();}
do_body : {$<vars>$ = dyna_push();}
{$<val>$ = cmdarg_stack >> 1; CMDARG_SET(0);}
- opt_block_param compstmt
+ opt_block_param bodystmt
{
$$ = new_do_body($3, $4);
dyna_pop($<vars>1);
~~~
I added tests for ensure to rubyspec, but there wasn't an obvious place to talk about rescue/else in this context (the spec for rescue only uses it in a begin/end block) It's probably fine as the spec for ensure does hit rescue, too, and they ultimately delegate to the same pieces. Not totally clear, though. I can do more with that if you need.
~~~diff
diff --git a/language/ensure_spec.rb b/language/ensure_spec.rb
index 13575fc..b14b0b5 100644
--- a/language/ensure_spec.rb
+++ b/language/ensure_spec.rb
@@ -124,3 +124,74 @@ describe "An ensure block inside a method" do
@obj.explicit_return_in_method_with_ensure.should == :ensure
end
end
+
+describe "An ensure block inside a do block" do
+ before :each do
+ ScratchPad.record []
+ end
+
+ it "is executed when an exception is raised in it's corresponding do block" do
+ begin
+ lambda do
+ ScratchPad << :begin
+ raise "An exception occured!"
+ ensure
+ ScratchPad << :ensure
+ end.should raise_error(RuntimeError)
+
+ ScratchPad.recorded.should == [:begin, :ensure]
+ end
+ end
+
+ it "is executed when an exception is raised and rescued in it's corresponding do block" do
+ begin
+ lambda do
+ ScratchPad << :begin
+ raise "An exception occured!"
+ rescue
+ ScratchPad << :rescue
+ ensure
+ ScratchPad << :ensure
+ end.call
+
+ ScratchPad.recorded.should == [:begin, :rescue, :ensure]
+ end
+ end
+
+ it "is executed even when a symbol is thrown in it's corresponding do block" do
+ begin
+ catch(:symbol) do
+ lambda do
+ ScratchPad << :begin
+ throw(:symbol)
+ rescue
+ ScratchPad << :rescue
+ ensure
+ ScratchPad << :ensure
+ end.call
+ end
+
+ ScratchPad.recorded.should == [:begin, :ensure]
+ end
+ end
+
+ it "is executed when nothing is raised or thrown in it's corresponding do block" do
+ lambda do
+ ScratchPad << :begin
+ rescue
+ ScratchPad << :rescue
+ ensure
+ ScratchPad << :ensure
+ end.call
+
+ ScratchPad.recorded.should == [:begin, :ensure]
+ end
+
+ it "has no return value" do
+ lambda do
+ :begin
+ ensure
+ :ensure
+ end.call.should == :begin
+ end
+end
~~~
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