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Mike Frysinger wrote: |
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|
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> On Monday 24 September 2007, Donnie Berkholz wrote: |
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>> |
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>> You could use C-style syntax here: |
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>> |
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>> (( use_errors++ )) |
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>> |
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>> I find it a bit more readable. |
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> |
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> i like to get anal and use ((++use_errors)) |
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> |
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> then again, it may also be more readable like so: |
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> use_errors=false |
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> if ... ; then |
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> ... |
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> use_errors=true |
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> fi |
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> if ... ; then |
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> ... |
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> use_errors=true |
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> fi |
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> ${use_errors} && die "..." |
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> -mike |
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|
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Integer arithmetic is generally quicker: |
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((use_errors++)) [or: use_errors=1 ] |
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.. |
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((use_errors)) && die 'meh' |
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-- although true and false are builtins in this case. |
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For stuff like for ((i=0;i<n;i++)) arithmetical context[1] is significantly |
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quicker than for i in {0..15} say, and more flexible (variable bound and |
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step-size, if desired.) |
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The boolean test on an integer eg ((use_errors)) is a metaphor I use a lot, |
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eg: ((quiet)) || echo oops; ((verbose>1)) && echo blah |
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It's handy as unset vars test to false, and also as the usual boolean values |
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apply, ie 0 is false, anything else is true. (Outside this context 0 is |
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true [success from cmd] and anything else is false [error code].) And ofc, |
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you don't need to put $ in front of your standard variables in this |
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context. |
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[1] http://wooledge.org/mywiki/ArithmeticExpression |
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-- |
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