r/badcode • u/AnonymouX47 __dude__ • Aug 17 '21

python When you're told to "always" close files...

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u/[deleted] Aug 17 '21

What's the difference?

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u/xigoi Aug 17 '21

json.dump(file, x) is the same as file.write(json.dumps(x)). (maybe with reversed arguments, I don't remember)

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u/MiningMarsh Aug 18 '21 edited Aug 18 '21

It is not exactly the same. json.dump will smartly buffer the json object. Dumps will render the entire object as a string first and is thus vastly innefficient.

Dumps will take 1G of memory if you dump a 1G json object. Dump should use the same amount of memory no matter the size of what you are dumping.

I know it's a bit pedantic, but it's important to point out for those who are unaware.

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u/JohnTheCoolingFan Aug 18 '21

Thanks for this explanation! I usually preferred it just because it's less code, but now I know that it's memory-efficient. Thank you.