Re: why not promote the plague ? (brace|rc|alternative|modern) syntax

Sorry, please ignore, was an old draft I accidentally sent.

On Mon, Dec 16, 2024 at 4:05 PM Mark J. Reed <[email protected]> wrote:

> Let's try this again:
>
> First, we have the standard syntax that works in any POSIX shell:
>>
>>     for var in val1 val2 val3; do command1; command2; done
>>     while command1; command2; do command3; command4; done
>>     until command1; command2; do command3; command4; done
>>     if command1; command2; then command3; command4; else command5;
>> command6; fi
>>
>> The C-style *for* loop is not part of POSIX, but is common to bash, ksh,
>> and zsh:
>>
>>     for (( init; condition; increment )) do command1; command2; done
>>
>> The *repeat* loop is purely a Zsh innovation not present in the other
>> shells:
>>
>>     repeat $times; do command1; command2; done
>>
>
>>
> All of the above have alternative syntax in Zsh that works irrespective of
>> the *SHORT_LOOPS* option.
>>
>
> So far, so correct, but I got a little too specific with the details.
>
>> Since all of these constructs have the form *intro-keyword *part1 *keyword1
>> *part2 *keyword2*, the basic idea is to replace *keyword1 *and *keyword2
>> *with curly braces.  But the *for*...*in *loop also has a *keyword0*,
>> namely *in*, which needs its own d
>>
>
>>     for var (val1 val2 val3) { command1; command2; }
>>     while (command1; command2) { command3; command4; }
>>     until (command1; command2) { command3; command4; }
>>     if (command1; command2) { command3; command4; } else { command5;
>> command6; }
>>     for (( init; condition; increment )) { command1; command2; }
>>     repeat $times { command1; command2; }
>>
>> NOTE: If the conditional command for while/until/if is a single ((...))
>> or [[...]] test, you don't need the extra parentheses around it.
>>
>> Finally, we have the Zsh "short" syntax, which works only with *setopt
>> SHORT_LOOPS*, and *only if the body is a single command*:
>>
>>     for var (val1 val2 val3) command1;
>>     while (command1; command2) command3
>>     until (command1; command2) command3
>>     if (command1; command2) command3;
>>     for (( init; condition; increment )) command1;
>>
>> NOTE: again, the parentheses can be omitted around a single ((...)) or
>> [[...]] test. Also, as far as I know, there's no way to attach an *else* to
>> an *if* when using the short syntax.
>>
>> On Sat, Dec 14, 2024 at 2:29 AM Marc Chantreux <[email protected]> wrote:
>>
>>> On Fri, Dec 13, 2024 at 07:07:17PM -0500, Lawrence Velázquez wrote:
>>> > Mikael's point was to distinguish between the alternative forms
>>> > and the SHORT_LOOPS forms.  None of your examples works without
>>> > SHORT_LOOPS
>>>
>>> thanks for noticing. which leads me to open zshmisc(1) and read
>>> read "ALTERNATE FORMS FOR COMPLEX COMMANDS". TIL that my coding
>>> style is actually a mix of the alternative form and SHORT_LOOPS
>>> and the difference is subtile:
>>>
>>>         « The  short  versions  below only work if sublist is of the
>>> form `{
>>>         list }' or if the SHORT_LOOPS option is set »
>>>
>>> regards
>>> --
>>> Marc Chantreux
>>>
>>>
>>
>> --
>> Mark J. Reed <[email protected]>
>>
>
>
> --
> Mark J. Reed <[email protected]>
>


-- 
Mark J. Reed <[email protected]>