[Info-vax] A DCL wish list of sorts...

[Stephen Hoffman]

On 2019-03-23 16:03:39 +0000, pcanagnostopoulos at gmail.com said:

> What was the intended purpose of the user common area in P1 space?

It's a somewhat nicer interface to a small Fortran or BASIC COMMON, 
where an app can read or write a string into the buffer.

In this case, somebody thought it would be interesting to have a block 
of virtual memory for this storage. Without backing storage.

It's one of various attempts headed toward having persistent storage 
for app configuration settings and related data, akin to how logical 
names are often (mis)used.

In this case as with various others, this API leaves the marshaling and 
unmarshaling of the data to the apps, and in this case uses virtual 
memory and not HDD or SSD storage.

With a means to write and read data to persistent storage without 
writing a whole pile of local code and a parser (and with all the "fun" 
that parsers can encounter), few folks would likely use the 
lib$put_common and lib$get_common calls.  Pragmatically, these 
lib$get_common and lib$put_common provide less than what a logical name 
and what a user-mode logical name for transient data, and a local name 
approach is more flexible.  Though the logical name API stinks, prior 
to lib$get_logical and lib$set_logical.

Related: 
https://developer.apple.com/documentation/foundation/userdefaults  
https://nshipster.com/nscoding/  etc,




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