Detailed File Information for One File
ambassador at fourthworld.com
Fri Apr 27 16:39:17 EDT 2018
Bob Sneidar wrote:
> Not to beat a severely wounded horse, but one reason for implementing
> a detailed file function (and probably why it hasn't been tackled) is
> that getting the detailed file information from a command shell is
> decidedly NOT straightforward.
Shell is great for things we can't do in LiveCode Script yet may not
warrant writing special C-based API interfaces for in LC Builder.
But in addition to the complexity of attempting to rely on such
interprocess communication across platforms, it also carries a certain
impact on memory and performance.
"Why run one process when you can run two at twice the price!" :)
In the enhancement request I cited earlier:
...Trevor raised a good point about instances where apparently macOS
sometimes disallows access to a folder even while allowing access to
specific files within it. It's hard for me to see how that would not be
a configuration error on any other system, but I trust Apple has a good
reason for that. And in such cases, we're hosed with any current LC
Script solution that needs access to the whole folder's content.
But for the other 99.9% of cases, using a scripted handler reduces the
task to a one-liner, here made even more convenient by allowing either
the detailed info returned in its LC-native comma-delimited format or as
an array if preferred:
put specialFolderPath("desktop")&"/test/Thisisafilename1000" into tPath
put fwFileInfo( tPath, "Array") into tA
if the result is not empty then
answer the result
put the keys of tA
function fwFileInfo pFile, pArrayFlag
-- Returns info for the file specified in pFile.
-- By default, returns the data in comma-delimited
-- form in the order specified by "detailed files".
-- With any value in the optional pArrayFlag arg
-- it will return an array with descriptive keys.
if there is not a file pFile then
return "No such file: "& pFile for error
set the itemdel to "/"
put urlEncode(last item of pFile) into tFileName
put item 1 to -2 of pFile into tPath
put files(tPath, "detailed") into tFiles
if the result is not empty then
return "Error getting file info: "& the result & \
" ("&sysError()&")" for error
put lineoffset(cr& tFileName&",", cr&tFiles) into tLineNum
put line tLineNum of tFiles into tInfo
if pArrayFlag is empty then
return tInfo for value
set the itemdel to ","
put 0 into i
"dateBackedUp,owner,group,permissions,MacType" into tFields
repeat for each item tItem in tInfo
add 1 to i
if i = 1 then put urlDecode(tItem) into tItem
put tItem into tA[item i of tFields]
return tA for value
Performance isn't bad (times shown in ms on Ubuntu 14.04 with Ext4 file
system) - each test was done with the slower form of the function call
that uses the array option:
Folder with 20 files: 0.000072
Folder with 5,000 files: 0.024766
Folder with 10,000 files: 0.042299
I'll leave it as an exercise for the reader to compare with benchmarks
for obtaining the same info via shell. But at a fraction of a
millisecond with LC Script even in an insanely large directory, I'll
wager the time to write the test would exceed any time saved over one's
Fourth World Systems
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