Modify the definition of SDImageFormat to extern to avoid creating multiple global variables #3699
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…ing multiple global variables
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Looks good for me. By the way, I want to talk about this This shit design (using a enum) is from the history SDWebImage 2.x, and changed into The most stupid is that this is actually not In SD 6.0, I'll totally remove this bad design, use class instead. // In SDWebImage Core repo
@interface SDImageFormat : NSObject
@property (readonly, nonnull) NSString *UTI;
@property (readonly, nonnull) NSString *preferredFilenameExtension;
@property (readonly, nonnull) NSString *preferredMIMEType;
@end
// Each coder repo, like JPEGXL
@interface SDImageFormat (JPEGXL)
@property (class, readonly) SDImageFormat *JPEGXL;
@end
// WebP repo
@interface SDImageFormat (WebP)
@property (class, readonly) SDImageFormat *WebP;
@end
// APNG
@interface SDImageFormat (APNG)
@property (class, readonly) SDImageFormat *APNG;
@end |
| return [self.class canEncodeToFormat:SDImageFormatWebP]; | ||
| default: | ||
| return NO; | ||
| if (format == SDImageFormatWebP) { |
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Compiler can do optimization based on enum cases number, these changes is no needed.
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The compiler reports an error when declare these variables as extern.
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So, is this cause API break (assume user use code like this in switch case?)
If so, why not totally break and use class declarations instead
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I remembered...In 5.c
This static declaration is written by me to allows "switch case" works
This code is indeed, so seems this is not possible in 5.x
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So, at least, we need to fix the 10+ individual coder repo as well (they use static declaration) Can we wait for the total break changes to use class based |
This is just a small optimization, looking forward to version 6.0 |
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I found that several formats about SDImageFormat are static variables defined in a header file. When the program is compiled and linked, any .m file that imports or indirectly imports this header will create a static variable inside the file. This results in an increase in useless binary size. In fact, only need to declare these variables as extern and assign values inside a certain .m file, so that there will only be one copy of these variables in the entire binary.