Re: Using file descriptors in Emacs

[Davis Herring <herring@lanl.gov>]

[All sbaugh@catern.com:]
>>> I suppose one could add the capability to pass in a process object as
>>> the source of input for a new process object. This could be implemented
>>> by forcing the passed-in process object to a state where it does not
>>> have (and cannot have) a process-filter function. Then the file
>>> descriptor used for input to the passed-in process object could be
>>> manipulated appropriately to make it the stdin of the new process
>>> object. The new process object in turn will be in a special state where
>>> it cannot accept input from Emacs.
[...]
>>> Then also it is necessary to handle redirecting to and from files
>>> without going through Emacs. That could be done by creating a new kind
>>> of process object which is created by opening a file, and then that can
>>> be passed in in the way I describe above.
[...]
> OK, that works for me. I guess it's not really different from the API I
> would have constructed for file descriptors.

Of course it's not any different: the phrases "[cannot] have ... a 
process-filter function", "a special state where it cannot accept input 
from Emacs", and especially "a new kind of process object which is 
created by opening a file" are telling you that these "generalized 
process objects" _are_ file descriptors.

Of course, this is already the case in Emacs: `make-network-process' 
makes a socket which (on POSIX at least) is a file descriptor.  The 
terminological confusion requires hedges like

> However, a network process has no process id, it cannot be signaled,
> and the status codes are different from normal processes.

from its documentation.

Davis

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