Switching off warnings temporarily

ruby-talk
1

Hi,

although always running code with '-w' is a good idea, you sometimes might like to switch off warnings locally, temporarily or both.

Now, http://www.caliban.org/ruby/rubyguide.shtml#warnings shows how to accomplish this (I just used 'yield' instead of 'call'ing a passed block).

(I know that assigning the result of puts to whatever *is* useless, its just to produce a warning)

---- Code starts here ----
def silently
   warn_level = $VERBOSE
   $VERBOSE = false
   res = yield
   $VERBOSE = warn_level
   res
end

bark = puts ( "Here be Dragons!" )

keep_silent = silently do
   any_line_of_code_will_do = 1
   puts ( "Creatures under a smooth surface" )
   nil
end

bark = puts ( "Here be dragons!" )

---- End of the Code ----

Remark: That really reads great: 'silently do ....' :slight_smile:
(We might like to see just the opposite 'verbosely do' with warnings switch on, no matter what.)

Now I came up with four ways to run this code: With or with out the '-w' command line option and with or without the (apparently useless) line commented out.

My expectation was ('is' actually) to get two warnings each way.
However

Code run with | No. of warnings

···

--------------------------------
#any... -w | 3
  any... -w | 3
#any... | 3
  any... | 2

To get the result I expect, I apparently need to run the code without the '-w' option and put some (useless) code before the line that might create a warning.

I have to admit that I just don't get it...
Why is that? Do you have any explanations?

Happy rubying

Stephan

--
Stephan Kämper/IT-Beratung http://www.stephankaemper.de
Quality Assurance / Software Test / Data Analysis

2

Stephan Kämper wrote:

---- Code starts here ----
def silently
  warn_level = $VERBOSE
  $VERBOSE = false
  res = yield
  $VERBOSE = warn_level
  res
end

bark = puts ( "Here be Dragons!" )

keep_silent = silently do
  any_line_of_code_will_do = 1
  puts ( "Creatures under a smooth surface" )
  nil
end

bark = puts ( "Here be dragons!" )

---- End of the Code ----

To get the result I expect, I apparently need to run the code without the '-w' option and put some (useless) code before the line that might create a warning.

Why is that? Do you have any explanations?

This happens on both Linux and WinXP, BTW. It's a recent Ruby snapshot on the Linux box and the most recent One-Click-Windows-Installer (1CWI) on WinXP.

Happy rubying

Stephan

3

[Stephan Kämper <Stephan.Kaemper@Schleswig-Holstein.de>, 2004-09-10 12.20 CEST]

---- Code starts here ----
def silently
  warn_level = $VERBOSE
  $VERBOSE = false
  res = yield
  $VERBOSE = warn_level
  res
end

bark = puts ( "Here be Dragons!" )

keep_silent = silently do
  any_line_of_code_will_do = 1
  puts ( "Creatures under a smooth surface" )
  nil
end

bark = puts ( "Here be dragons!" )

---- End of the Code ----

Remark: That really reads great: 'silently do ....' :slight_smile:
(We might like to see just the opposite 'verbosely do' with warnings
switch on, no matter what.)

Now I came up with four ways to run this code: With or with out the '-w'
command line option and with or without the (apparently useless) line
commented out.

My expectation was ('is' actually) to get two warnings each way.
However

Code run with | No. of warnings
--------------------------------
#any... -w | 3
any... -w | 3
#any... | 3
any... | 2

To get the result I expect, I apparently need to run the code without
the '-w' option and put some (useless) code before the line that might
create a warning.

I have to admit that I just don't get it...
Why is that? Do you have any explanations?

I can't explain the "any_line_will_do" thing, but the warnings you are
getting ("don't puts spaces before arg parens") are compile-time (ie, when
your code is read). With $VERBOSE you can disable run-time warnings only
(because the variable is set at run time...).

* Compile time:
$ ruby -we 'puts ("Hi")'
-e:1: warning: (...) interpreted as grouped expression
Hi

$ ruby -we '$VERBOSE=nil; puts ("Hi")'
-e:1: warning: (...) interpreted as grouped expression
Hi

* Run time:
$ ruby -we 'A=1; A=2'
-e:1: warning: already initialized constant A

$ ruby -we '$VERBOSE=nil; A=1; A=2'

(no warning)

···

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