bug-bash
[Top][All Lists]
Advanced

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: Inline `ifdef style` debugging


From: Roger
Subject: Re: Inline `ifdef style` debugging
Date: Mon, 8 Aug 2011 09:09:15 -0800
User-agent: Mutt/1.5.21 (2010-09-15)

> On Mon, Aug 08, 2011 at 08:56:36AM -0500, Dennis Williamson wrote:
>On Mon, Aug 8, 2011 at 3:47 AM, Roger <address@hidden> wrote:
>> I'm doing some research for one of my scripts and always liked the C style
>> ifdef inline debug statements.

...

>Another way to write the _debug() function:
>
>#!/bin/bash
>debug=true
>
># Function to optionally handle executing included debug statements
>_debug()
>{
>   debug && "$@"
>}
>
>Using this method, you don't really need a function at all. You can
>just use the debug variable directly (you could use an underscore
>prefix):
>
>   $debug && printf "Checking depedencies...\n"
>
>   $debug && {
>        # it's even more like ifdef since you can conditionally
>execute blocks of code
>        foo
>        bar
>    }
>
>You have to make sure that $debug contains only "true" or "false" or
>you'll get errors. There are exceptions to this, but the complexity
>isn't worth the effort.

This is interesting because I'm guessing it might save one or two CPU
cycles, although it still does use a test at "&&", and is still
readable, if not more readable then before.

>I prefer using lowercase or mixed case variable names by habit to
>reduce the chances of name collisions with predefined variables
>(although that's not an issue with this specific script).

I know the system capitalized defined variables, so I usually just use
all capitalized variable for global script variables within the
header/top of the bash script.  I've heard of the risk of collision,
and have tried mixed-case variable names, but they were not as readable
and the risk seemed more minimal ... unless a Linux distribution makes
up a system variable that conflicts with one of my all capitalized
variable names.

I then use lower case for locally used variables within the Bash script or
within the functions of the script.  Similar to C.  It just makes good
sense, and I know where to look for predefined capitalized variable names
for their definition.

>Since you're writing a script for Bash, you might as well use Bash
>features. Here is the main line of your function a couple of more
>different ways (using the original capitalization and value):
>
>   [[ $DEBUG != 0 ]] && "$@"            # string comparison
>   (( DEBUG != 0 )) && "$@"              # integer comparison (note,
>the $ is unnecessary)

Yup.  I was thinking of sticking with 0's & 1's, as text comparison
requires more CPU cycles ... although negligible these days, it's just
good programming practice.

-- 
Roger
http://rogerx.freeshell.org/



reply via email to

[Prev in Thread] Current Thread [Next in Thread]