[rust-dev] Why does string formatting in Rust have to be different from other languages?

2013-11-18 Thread Derek Chiang 
Hi all,

I'm a newcomer to Rust.  One of the things that I find confusing is the use
of {} in formatted strings.  In all other languages I've ever used, it's
always %.  So instead of writing %d, you write {:d} in Rust.  Why is
this so?  What benefits do we get?

Thanks,
Derek
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Re: [rust-dev] Why does string formatting in Rust have to be different from other languages?

2013-11-18 Thread Daniel Micay 
On Mon, Nov 18, 2013 at 2:02 AM, Derek Chiang derekchian...@gmail.com wrote:
 Hi all,

 I'm a newcomer to Rust.  One of the things that I find confusing is the use
 of {} in formatted strings.  In all other languages I've ever used, it's
 always %.  So instead of writing %d, you write {:d} in Rust.  Why is
 this so?  What benefits do we get?

 Thanks,
 Derek

It's the syntax used by C# and modern Python:

http://msdn.microsoft.com/en-us/library/system.string.format(v=vs.110).aspx
http://docs.python.org/2/library/string.html#format-string-syntax
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Re: [rust-dev] Why does string formatting in Rust have to be different from other languages?

2013-11-18 Thread Alex Crichton 
Rust’s old fmt! syntax also used % instead of {}. The reason for the switch was 
to primarily support compatibility with an internationalization-style scheme of 
string formatting. The main benefit of {} of % is that you can nest {} inside 
of another format, whereas with % you’re limited to just one format. That being 
said, this effort has not gone underway just yet.

As Daniel also pointed out, the syntax was drawn from other languages instead 
of inventing one fresh, so it should be familiar to at least some programmers. 
If you’re curious about how the format syntax works, there’s documentation 
which can be found at http://static.rust-lang.org/doc/master/std/fmt/index.html.

Hope that clears up any confusion!

On Nov 17, 2013, at 11:02 PM, Derek Chiang derekchian...@gmail.com wrote:

 Hi all,
 
 I'm a newcomer to Rust.  One of the things that I find confusing is the use 
 of {} in formatted strings.  In all other languages I've ever used, it's 
 always %.  So instead of writing %d, you write {:d} in Rust.  Why is this 
 so?  What benefits do we get?
 
 Thanks,
 Derek
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