Subject: Getting a replacement for sprintf ?!
In-Reply-To: <ef94acf8-bc29-f666-0b19-efdd505f10d9@virtuell-zuhause.de>
References: <ef94acf8-bc29-f666-0b19-efdd505f10d9@virtuell-zuhause.de>
Message-ID: <B1034373-B330-4661-8EF9-4E64638EFCD2@info-igor.org>

Having used the C format string primitives for a long time, I seem to be comfortable with them and found them to be extremely flexible. I think there there isn?t a limit on string lengths with sprintf other than the Igor built in limit.

sprintf is an operation and not a function in Igor terminology, to handle the variety of different number and type of optional parameters.

Your example is simple but doesn?t allow the full flexibility of the C string format specifiers where resolution and digits can be specified dynamically in the format string itself. I think one could write a function with variable parameters to replace sprintf and avoid the temporary string but haven?t found it worthwhile.

Or having a sprintf function that returns a string (sprintff ???) could be a wish list for Igor 9?

-Scott


> On Feb 24, 2019, at 1:17 PM, Thomas Braun <thomas.braun at virtuell-zuhause.de> wrote:
>
> Hi Igorians,
>
> since quite some time I'm starting to dislike the sprintf function.
>
> Main reason is that I need to create a temporary string to be able to work with it and
> also that it can not be used in arbitrary code as e.g. %s is limited to x number of characters.
>
> Since quite some time I've been using fmtlib [1] in my C++ projects.
> In short it allows you to write something like
>
> fmt::format("The answer is {}.", 42);
>
> and that returns a string with the contents ?The answer is 42.?.
>
> Now there is no use in trying to get that exact syntax working in Igor Pro.
>
> But one could get quite close. Here is a hacky hack example:
>
> Function Examples()
>
> print f("Hi {s_a}!", s_a = "HAL")
> print f("Are you up to counting from 0 to {v_a}?", v_a = 10)
> print f("Sure ;) Wanna see {w_a}?", w_a = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10})
> print f("In this case have fun with {s_a} and {v_a}s.", v_a=0, s_a="ones")
>
> End
>
> Function/S f(format, [v_a, s_a, w_a])
> string format
> variable v_a
> string s_a
> WAVE w_a
>
> variable numDefaultParams, i
> string str, buf, w_buf
>
> if(ParamIsDefault(v_a))
> numDefaultParams += 1
> endif
>
> if(ParamIsDefault(s_a))
> numDefaultParams += 1
> endif
>
> if(ParamIsDefault(w_a))
> numDefaultParams += 1
> endif
>
> str = format
>
> if(numDefaultParams == 0)
> // TODO check that str does not contain {}
> return str
> endif
>
> if(!ParamIsDefault(v_a))
> // TODO make %g configurable from {}
> sprintf buf, "%g", v_a
> str = ReplaceString("{v_a}", str, buf)
> endif
>
> if(!ParamIsDefault(s_a))
> // TODO make configurable
> str = ReplaceString("{s_a}", str, s_a)
> endif
>
> if(!ParamIsDefault(w_a))
> // TODO make configurable and support dimensions larger than 1D
> // and also other wave types
> w_buf = "["
> for(i = 0; i < DimSize(w_a, 0); i += 1)
> sprintf buf, "%g", w_a[i]
> w_buf += buf
>
> if(i != DimSize(w_a, 0) - 1)
> w_buf += ", "
> endif
> endfor
> w_buf += "]"
>
> str = ReplaceString("{w_a}", str, w_buf)
> endif
>
> return str
> End
>
> which gives
>
> ?examples()
> Hi HAL!
> Are you up to counting from 0 to 10?
> Sure ;) Wanna see? -> [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
> In this case have fun with ones and 0s.
>
> and this is already quite nice (I think) because it avoids both my main problems with sprintf.
>
> My main problem at the moment is that it does not scale with the number of characters per type. If we would support up to 8 characters after the "_" we have already
>
> ?print/D 26^8*3
> 626481193728
>
> combinations and thus a dump approach would need that many optional parameters. And to be usable we would need a way to iterate over them in a way with has sub-linear complexity.
>
> And we would probably also hit a hard-coded limit of the number of optional parameters or maximum line length or ....
>
> Thoughts?
>
> Thomas
>
> [1]: https://github.com/fmtlib/fmt
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