> On Jun 21, 2016, at 15:48, Jonathan Cotton via swift-evolution
> <swift-evolution@swift.org> wrote:
>
> I'd support $() as is in use by other languages, including Kotlin, as
> mentioned it seems less disruptive and more inline with the tokenised
> parameters that are already supported in closures.
>
>> On 21 Jun 2016, at 21:43, Kenny Wyland via swift-evolution
>> <swift-evolution@swift.org> wrote:
>>
>> Hi all,
>>
>> I'm new to the list and I just searched through the archives as best I could
>> to see if someone else had already brought this up, but I didn't find
>> anything. Forgive me if this horse has been beaten.
>>
>> I find that typing \(var) is very disruptive to my typing flow. The more I
>> code in Swift, the more I like it, but every time I'm coding and then have
>> to hiccup while typing \ then ( causes me to be annoyed. I know, it's minor,
>> but it isn't a key combination that flows quickly.
>>
>> I would much rather have $() or perhaps ${} (like Groovy lang) or perhaps
>> @() to go along with other uses of @ throughout the language.
>>
>> A shifted key, like $ or @, followed by another shifted key like (, allows
>> for a much faster flow and they are much closer to the home keys than \
>> which is nearly as far from home keys as possible (and awkward).
>>
>> Thoughts?
>>
>> Kenny Wyland
>> InADayDevelopment.com <http://inadaydevelopment.com/>
I have to disagree - The \ syntax is consistent with other string escape
sequences (\n etc.) and reads naturally to me in that regard. Additionally, the
\ is very visually distinctive in a string, much moreso than the "traditional"
$ variable marker. Almost every language I’ve seen using $ for interpolation in
strings is doing so because it also uses it as a variable prefix in non-string
contexts. To top it off, using $ instead would, for me, just add yet another
language for which I have to remember "does the $ go inside or outside the name
delimiter braces/brackets/whatever?", "is it parenthesis, braces, brackets, or
some other delimiter for variable names?", "what kind of expressions can I use
in this context?", "can I use interpolation without any delimiters for simple
cases?", etc. See also PHP, Perl, ten flavors of shell scripts, JavaScript,
JSP/ASP, XPath, and so forth. The \() syntax is unique to Swift and therefore
very easy to remember.
I also don’t see that Swift carries an expectation of being able to use a
syntax which is traditionally confined to interpreted/scripting languages, and
even there $ is by no means ubiquitous. Here are just a few counterexamples
among various languages:
- C (printf formats)
- C++ (stream modifiers)
- Objective-C (NSString formats)
- C# ($, but with the unusual syntax $"blah {foo} blah")
- Lua (printf formats and language hacks)
- Python (printf formats with trailing "% (tuple)" syntax)
- Ruby ("#{}")
- Java (printf formats)
There’s an obvious pattern in these example, which brings to something I
_would_ like to see for string interpolation in Swift: Better control over the
precise representation of the data. I’m sure the topic has been done to death
many times before, but I haven’t found any solid information at a quick search,
so I apologize if this is all old hat.
Anyway - Creating, configuring, and invoking various Formatter types in order
to present data in the proper fashion is an option, and a preferable one when
the data is intended for user consumption (especially to get the maximum
support from localization). But for logging, debugging, parsing of textual
formats, writing textual formats, etc., I almost always want a traditional
C/POSIX/ISO representation as easily provided by printf()-style specifiers. 99%
of the time when I want to do an number-to-string (integer or otherwise)
conversion especially, I’m being specific about the appearance of the number.
For example, for a hex representation of sockaddr_in.sin_addr.s_addr, I would
in other languages write "printf("0x%08x", address.sin_addr.s_addr);", or
"%02hhu" times four to get dotted-decimal notation. (Ignoring for the moment
the existence of inet_ntop() for the sake of the example :). In Swift, I
currently have to make a call to printf(), fprintf(), dprintf(),
NSString(format:), asprintf() (with a wrapper to deal with getting a
Swift.String from allocated memory), etc. A configured NumberFormatter instance
is a great deal more code - even NumberFormatter.localizedString(from: foo,
number: .decimal) is very verbose, and that *still* doesn’t yield the same
level of format control!).
And to top it off, these still carry the traditional problem of printf()
formats - separation between the format specifier and the data that format
applies to. I’m sure most of us have at one time or another written a printf()
with enough arguments that it was easy to lose track of them and end up being
very grateful for the existence of -Werror=format (and frustrated that
__attribute__((format(..))) is as limited as it is :).
I’m not sure exactly what form support for formatted data in interpolated
strings would take in Swift, but it’s certainly one of the things I find myself
actively missing on a regular basis, and I do have some ideas on how to go
about it, if it isn’t already under discussion/development.
-- Gwynne Raskind
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