2012/12/10 Maxim Gonchar <gma...@gmail.com>: > Hi Cheer, > > since you already use the additional function, it worth looking at the > 'find' command, which can do all the complicated job which can not be done > with simple globbing. > > regards, > Maxim > > > On Sun, 09 Dec 2012 17:43:59 +0400, Cheer Xiao <xiaqq...@gmail.com> wrote: > >> Hi all, >> >> For those not acquainted with zsh: extended globbing is one of the >> many features of zsh that allows you to match files satisfying a given >> criteria in a inline manner (instead of going through a loop). For >> example, "echo abc*(/)" gives you all directories with names starting >> with "abc" in current directory, while "rm .*(@)" removes all symlinks >> with names starting with ".", etc. It is a useful feature, but I don't >> really like the arcane syntax. >> >> Fish doesn't have extended globbing (which is good actually :-), so >> I'm tempted to write this: >> >> function filter >> set predicate $argv[1] >> for i in (seq 2 (count $argv)) >> test $predicate $argv[$i]; and echo $argv[$i] >> end >> end >> >> So now I write "echo (filter -d abc*)" and "rm (filter -L .*)" to >> achieve the same effect as "echo abc*(/)" and "rm .*(@)" in zsh. It is >> more verbose, but the readability is considerably better; it also >> allows you to reuse the knowledge of the "test" builtin. >> >> This works fine until, of course, you start to encounter file names >> containing newlines. Try this: >> >> cd (mktemp -d) >> mkdir 'a >> b' >> count * >> count (filter -d *) >> >> Clearly, The problem stems from the fact that when fish expands the >> command substitution (filter -d *), filenames echo'ed by "filter" run >> together before being split on newlines to render the substituted >> words. A newline in one of the filenames is then indistinguishable >> with two filenames. >> >> So this leads to my proposal: >> >> * When evaluating a fish function, maintain an alternative output >> buffer besides stdout. The buffer is actually a dynamic-sized list >> (std::vector for C++ programmers) of strings. Introduce a new builtin >> (say "put") to write to that buffer. >> >> * Exactly one of the two output buffers (let's call them stdout and >> altout) should be active within a function. >> >> * Within functions, calling "put" activates the altout and closes >> stdout. Each invocation of "put" with k arguments appends k new >> elements to altout. (The relationship between altout and stdout still >> needs some thoughts though.) >> >> * When command substitution is performed, it is checked which of >> stdout and altout is active (the latter is only possible for fish >> functions; external commands always have only stdout active). If >> altout is active, the elements in altout are substituted directly. If >> stdout is active, the content in stdout is split on newlines before >> being substituted (as is currently done). >> >> * When altout is written to when there is no enclosing command >> substitution (eg. calling "put" on the prompt), anything written to it >> is directed to stdout plus a newline. >> >> With altout I can write my "filter" by replacing "echo" with "put" and >> it's now newline-safe. >> >> Being able to output arrays of strings can be of many other uses - >> actually it enables you to write any array manipulating functions in >> an easy way. >> >> If the newline-in-filenames stuff sounds too invented and unlikely, >> consider why shells need real arrays instead of strings joined by >> delimiters (be it whitespace or newlines) at all. Actually, one of the >> favorite things about fish is its clean array syntax, it is a really >> nice thing. I think fish deserves the added expressive power. :) >> >> >> -- >> Regards, >> Cheer Xiao >> >> >> ------------------------------------------------------------------------------ >> LogMeIn Rescue: Anywhere, Anytime Remote support for IT. Free Trial >> Remotely access PCs and mobile devices and provide instant support >> Improve your efficiency, and focus on delivering more value-add services >> Discover what IT Professionals Know. Rescue delivers >> http://p.sf.net/sfu/logmein_12329d2d >> _______________________________________________ >> Fish-users mailing list >> Fish-users@lists.sourceforge.net >> https://lists.sourceforge.net/lists/listinfo/fish-users
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