Movatterモバイル変換

[Python-Dev] PEP 471 -- os.scandir() function -- a better andfaster directory iterator

• Previous message:[Python-Dev] PEP 471 -- os.scandir() function -- a better and faster directory iterator
• Next message:[Python-Dev] PEP 471 -- os.scandir() function -- a better and faster directory iterator
• Messages sorted by:[ date ][ thread ][ subject ][ author ]

On Sat, Jun 28, 2014 at 03:55:00PM -0400, Ben Hoyt wrote:> Re is_dir etc being properties rather than methods:[...]> The problem with this is that properties "look free", they look just> like attribute access, so you wouldn't normally handle exceptions when> accessing them. But .lstat() and .is_dir() etc may do an OS call, so> if you're needing to be careful with error handling, you may want to> handle errors on them. Hence I think it's best practice to make them> functions().I think this one could go either way. Methods look like they actually re-test the value each time you call it. I can easily see people not realising that the value is cached and writing code like this toy example:# Detect a file change.t = the_file.lstat().st_mtimewhile the_file.lstat().st_mtime == t:     sleep(0.1)print("Changed!")I know that's not the best way to detect file changes, but I'm sure people will do something like that and not realise that the call to lstat is cached.Personally, I would prefer a property. If I forget to wrap a call in a try...except, it will fail hard and I will get an exception. But with a method call, the failure is silent and I keep getting the cached result.Speaking of caching, is there a way to freshen the cached values?-- Steven

• Previous message:[Python-Dev] PEP 471 -- os.scandir() function -- a better and faster directory iterator
• Next message:[Python-Dev] PEP 471 -- os.scandir() function -- a better and faster directory iterator
• Messages sorted by:[ date ][ thread ][ subject ][ author ]