But if you rely on these subtleties this is hardly a "basic feature" that the language is lacking. In fact, I imagine File.Exists()/OF_EXISTS also opens the file (then immediately closes it).
If you actually open a file, you update it's access time, and you interfere with the process that should actually open the file. Those both break perfectly simple business logic.
The documentation for OF_EXISTS literally says it will open then close it. I leave to your imagination whether this updates the (very poorly defined) access time or not, but for sure you "interfere" with other processes...
If you want to get the access time, why don't you just query the access time? Which is likely the only thing almost universally guaranteed not to change it...
And I'm sure VB6 has an API for that, considering that VBA had a global API for it (FileDateTime).
(Which is, btw, yet another way to one-line check if a file exists).
You don't use exists and then open a file. If you actually want to open a file, you open it or fail. You don't check if it's ok and then do it, you do it and then check if it failed.
exists followed by open is a pointless exists because anything can happen in between.
Conversely, if you are neither the producer nor consumer of the file at this time, you don't want to actually open it just as a way to stat it, because actually opening it updates it's access time and interferes with the actual consumer(s). Even read-only non-exclusive.
But if you rely on these subtleties this is hardly a "basic feature" that the language is lacking. In fact, I imagine File.Exists()/OF_EXISTS also opens the file (then immediately closes it).
It better not!
If you actually open a file, you update it's access time, and you interfere with the process that should actually open the file. Those both break perfectly simple business logic.
The documentation for OF_EXISTS literally says it will open then close it. I leave to your imagination whether this updates the (very poorly defined) access time or not, but for sure you "interfere" with other processes...
If you want to get the access time, why don't you just query the access time? Which is likely the only thing almost universally guaranteed not to change it... And I'm sure VB6 has an API for that, considering that VBA had a global API for it (FileDateTime).
(Which is, btw, yet another way to one-line check if a file exists).
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But then the only way to make sure that you can open a file is to actually open it.
You don't use exists and then open a file. If you actually want to open a file, you open it or fail. You don't check if it's ok and then do it, you do it and then check if it failed.
exists followed by open is a pointless exists because anything can happen in between.
Conversely, if you are neither the producer nor consumer of the file at this time, you don't want to actually open it just as a way to stat it, because actually opening it updates it's access time and interferes with the actual consumer(s). Even read-only non-exclusive.
You can use it as an improvised lock.
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