SE-0028 Debugging Identifier #filename


(Michael Peternell) #1

Hi,

I have a small question about SE-0028, "Modernizing Swift's Debugging Identifiers"
https://github.com/apple/swift-evolution/blob/master/proposals/0028-modernizing-debug-identifiers.md

I think this is a great feature, because I think it makes it clearer that there a special syntactic rules involved when the debug-identifier is written as "#file" instead of __FILE__.

Will "#filename" also be included in Swift 3.0? It's basically the same as #file.lastPathComponent, but with the additional safety feature that you cannot find the full pathnames when analyzing the executable file. I saw it mentioned in the proposal, but I'm not sure if it was accepted, or if it is just an idea for some later Swift version. I think the idea is great. I think adding #filename would be an improvement. In the past, when writing Objective-C, I used the __FILE__ macro quite a few times, usually for writing logging macros. And in the function that gets called eventually, I always strip away all but the last path component (using strrchr()). ("#file" should stay, I'm not suggesting that it is replaced with "#filename", I only suggest that "#filename" be added.)

Another alternative would be to make "#file.lastPathComponent" a debugging-identifier that is handled by the preprocessor, so we could write something like

    func myLog(msg: String, filename: String = #file.lastPathComponent, line: Int = #line) { ... }

and the preprocessor would optimize away the call to lastPathComponent, so that the lastPathComponent function doesn't have to be called at runtime.

Regards,
Michael


(Erica Sadun) #2

This was already brought up on list. See: [Pitch] Introducing #fileName debug identifier. Module-relative path seems to be most highly requested form of #file. Chris Lattner had the final word,

"In this case, I don’t think that more is better. Having too many options and knobs is not good for anyone. Having #file produce the module-relative path (including the module name) serves all of the use-cases that I’m aware of, since you can further slice and dice it to get the base file name out. "

To my best understanding this was the end of the discussion, leaving two loose threads:
  1. Actually introducing the change, which I'm not sure if it needs a bug report or what
  2. Gregorizing the #function literal to match the new method/function naming scheme

-- E

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On Apr 11, 2016, at 3:48 PM, Michael Peternell via swift-evolution <swift-evolution@swift.org> wrote:

Hi,

I have a small question about SE-0028, "Modernizing Swift's Debugging Identifiers"
https://github.com/apple/swift-evolution/blob/master/proposals/0028-modernizing-debug-identifiers.md

I think this is a great feature, because I think it makes it clearer that there a special syntactic rules involved when the debug-identifier is written as "#file" instead of __FILE__.

Will "#filename" also be included in Swift 3.0? It's basically the same as #file.lastPathComponent, but with the additional safety feature that you cannot find the full pathnames when analyzing the executable file. I saw it mentioned in the proposal, but I'm not sure if it was accepted, or if it is just an idea for some later Swift version. I think the idea is great. I think adding #filename would be an improvement. In the past, when writing Objective-C, I used the __FILE__ macro quite a few times, usually for writing logging macros. And in the function that gets called eventually, I always strip away all but the last path component (using strrchr()). ("#file" should stay, I'm not suggesting that it is replaced with "#filename", I only suggest that "#filename" be added.)

Another alternative would be to make "#file.lastPathComponent" a debugging-identifier that is handled by the preprocessor, so we could write something like

   func myLog(msg: String, filename: String = #file.lastPathComponent, line: Int = #line) { ... }

and the preprocessor would optimize away the call to lastPathComponent, so that the lastPathComponent function doesn't have to be called at runtime.

Regards,
Michael

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Supplement #file, #line, and #function with #context