Hi
I wrote a single script which should do: write a file -> open this file -> write another different file. I put the write expressions in the right sequence, but it seems that the second one cannot happen because the file created by the first write function has not yet been created at the time the second function is invoked. Does anyone have a suggestion about this? Thanks.
Best, Giuseppe
Hi Giuseppe, a little self-contained example would be appreciated! Best, Christian
On Tue, Mar 12, 2019 at 11:19 AM Giuseppe G. A. Celano celano@informatik.uni-leipzig.de wrote:
Hi
I wrote a single script which should do: write a file -> open this file -> write another different file. I put the write expressions in the right sequence, but it seems that the second one cannot happen because the file created by the first write function has not yet been created at the time the second function is invoked. Does anyone have a suggestion about this? Thanks.
Best, Giuseppe
Hi Guiseppe,
The following pattern is supposed to / does work:
file:write("1.txt", "Written to 1.txt"), file:write("2.txt", file:read-text("1.txt")), "Read from 2.txt: " || file:read-text('2.txt')
Could you maybe elaborate a bit more on your code?
Best from Konstanz
Michael
Am 12.03.2019 um 11:19 schrieb Giuseppe G. A. Celano celano@informatik.uni-leipzig.de:
Hi
I wrote a single script which should do: write a file -> open this file -> write another different file. I put the write expressions in the right sequence, but it seems that the second one cannot happen because the file created by the first write function has not yet been created at the time the second function is invoked. Does anyone have a suggestion about this? Thanks.
Best, Giuseppe
let $o := file:create-dir("/Users/mycomputer/prova") let $o2 := file:write("/Users/mycomputer/prova/file1.xml", "ciao") let $o3 := file:write("/Users/mycomputer/prova/file2.xml", file:read-text("/Users/mycomputer/prova/file1.xml")) return ($o, $o2, $o3)
This actually works. In my real example the writing of $o2 requires e few seconds. It might be that $o3 is evaluated while $o2 is still running?
Dr. Giuseppe G. A. Celano DFG-project leader http://gepris.dfg.de/gepris/projekt/408121292 Universität Leipzig Institute of Computer Science, NLP Augustusplatz 10 Tel: +4934132223 04109 Leipzig Deutschland
E-mail: celano@informatik.uni-leipzig.de mailto:celano@informatik.uni-leipzig.de Web site 1: http://asv.informatik.uni-leipzig.de/en/staff/Giuseppe_Celano http://asv.informatik.uni-leipzig.de/en/staff/Giuseppe_Celano Web site 2: https://sites.google.com/site/giuseppegacelano/ https://sites.google.com/site/giuseppegacelano/
On Mar 12, 2019, at 11:27 AM, Michael Seiferle ms@basex.org wrote:
Hi Guiseppe,
The following pattern is supposed to / does work:
file:write("1.txt", "Written to 1.txt"), file:write("2.txt", file:read-text("1.txt")), "Read from 2.txt: " || file:read-text('2.txt')
Could you maybe elaborate a bit more on your code?
Best from Konstanz
Michael
Am 12.03.2019 um 11:19 schrieb Giuseppe G. A. Celano <celano@informatik.uni-leipzig.de mailto:celano@informatik.uni-leipzig.de>:
Hi
I wrote a single script which should do: write a file -> open this file -> write another different file. I put the write expressions in the right sequence, but it seems that the second one cannot happen because the file created by the first write function has not yet been created at the time the second function is invoked. Does anyone have a suggestion about this? Thanks.
Best, Giuseppe
Could you attach one of the queries that you mentioned in your first question (i.e., that didn’t work for you)? We might then be able to resolve why $o2 seems to take longer than you would expect it to take.
In general, it’s recommendable not to bind code to variables if the expression does not yield any results. I would probably rewrite your code as follows:
let $dir := "/Users/mycomputer/prova/" return ( file:create-dir($dir), file:write($dir || "file1.xml", "ciao"), file:write($dir || "file2.xml", file:read-text($dir || "file1.xml")) )
As XQuery is a function language, it would be allowed for a processor to run the second write call before the first. However, we enforce the evaluation of the original expression if expressions are non-deterministic or side-effecting (which is the case for all of your function calls).
On Tue, Mar 12, 2019 at 11:44 AM Giuseppe G. A. Celano celano@informatik.uni-leipzig.de wrote:
let $o := file:create-dir("/Users/mycomputer/prova") let $o2 := file:write("/Users/mycomputer/prova/file1.xml", "ciao") let $o3 := file:write("/Users/mycomputer/prova/file2.xml", file:read-text("/Users/mycomputer/prova/file1.xml")) return ($o, $o2, $o3)
This actually works. In my real example the writing of $o2 requires e few seconds. It might be that $o3 is evaluated while $o2 is still running?
Dr. Giuseppe G. A. Celano DFG-project leader Universität Leipzig Institute of Computer Science, NLP Augustusplatz 10 Tel: +4934132223 04109 Leipzig Deutschland
E-mail: celano@informatik.uni-leipzig.de Web site 1: http://asv.informatik.uni-leipzig.de/en/staff/Giuseppe_Celano Web site 2: https://sites.google.com/site/giuseppegacelano/
On Mar 12, 2019, at 11:27 AM, Michael Seiferle ms@basex.org wrote:
Hi Guiseppe,
The following pattern is supposed to / does work:
file:write("1.txt", "Written to 1.txt"), file:write("2.txt", file:read-text("1.txt")), "Read from 2.txt: " || file:read-text('2.txt')
Could you maybe elaborate a bit more on your code?
Best from Konstanz
Michael
Am 12.03.2019 um 11:19 schrieb Giuseppe G. A. Celano celano@informatik.uni-leipzig.de:
Hi
I wrote a single script which should do: write a file -> open this file -> write another different file. I put the write expressions in the right sequence, but it seems that the second one cannot happen because the file created by the first write function has not yet been created at the time the second function is invoked. Does anyone have a suggestion about this? Thanks.
Best, Giuseppe
The code is long, because there are many functions. However, I did something like the following, and it works:
let $o := file:create-dir("/Users/mycomputer/prova") let $o3 := file:write("/Users/mycomputer/prova/file2.xml", (file:write("/Users/mycomputer/prova/file1.xml", "ciao"), file:read-text("/Users/mycomputer/prova/file1.xml")) )
return ($o, $o3)
The evaluation of the first write() is forced to happen and conclude before the second write() is evaluated. I am still experimenting on this, but would there be a way to force completion of evaluation without embedding?
On Mar 12, 2019, at 11:44 AM, Giuseppe G. A. Celano celano@informatik.uni-leipzig.de wrote:
let $o := file:create-dir("/Users/mycomputer/prova") let $o2 := file:write("/Users/mycomputer/prova/file1.xml", "ciao") let $o3 := file:write("/Users/mycomputer/prova/file2.xml", file:read-text("/Users/mycomputer/prova/file1.xml")) return ($o, $o2, $o3)
This actually works. In my real example the writing of $o2 requires e few seconds. It might be that $o3 is evaluated while $o2 is still running?
Dr. Giuseppe G. A. Celano DFG-project leader http://gepris.dfg.de/gepris/projekt/408121292 Universität Leipzig Institute of Computer Science, NLP Augustusplatz 10 Tel: +4934132223 04109 Leipzig Deutschland
E-mail: celano@informatik.uni-leipzig.de mailto:celano@informatik.uni-leipzig.de Web site 1: http://asv.informatik.uni-leipzig.de/en/staff/Giuseppe_Celano http://asv.informatik.uni-leipzig.de/en/staff/Giuseppe_Celano Web site 2: https://sites.google.com/site/giuseppegacelano/ https://sites.google.com/site/giuseppegacelano/
On Mar 12, 2019, at 11:27 AM, Michael Seiferle <ms@basex.org mailto:ms@basex.org> wrote:
Hi Guiseppe,
The following pattern is supposed to / does work:
file:write("1.txt", "Written to 1.txt"), file:write("2.txt", file:read-text("1.txt")), "Read from 2.txt: " || file:read-text('2.txt')
Could you maybe elaborate a bit more on your code?
Best from Konstanz
Michael
Am 12.03.2019 um 11:19 schrieb Giuseppe G. A. Celano <celano@informatik.uni-leipzig.de mailto:celano@informatik.uni-leipzig.de>:
Hi
I wrote a single script which should do: write a file -> open this file -> write another different file. I put the write expressions in the right sequence, but it seems that the second one cannot happen because the file created by the first write function has not yet been created at the time the second function is invoked. Does anyone have a suggestion about this? Thanks.
Best, Giuseppe
As indicated, don’t bind expressions to variables if they yield empty sequences (here: $o, $o3), and it should be easier to reproduce what’s happening.
On Tue, Mar 12, 2019 at 12:04 PM Giuseppe G. A. Celano celano@informatik.uni-leipzig.de wrote:
The code is long, because there are many functions. However, I did something like the following, and it works:
let $o := file:create-dir("/Users/mycomputer/prova") let $o3 := file:write("/Users/mycomputer/prova/file2.xml", (file:write("/Users/mycomputer/prova/file1.xml", "ciao"), file:read-text("/Users/mycomputer/prova/file1.xml")) )
return ($o, $o3)
The evaluation of the first write() is forced to happen and conclude before the second write() is evaluated. I am still experimenting on this, but would there be a way to force completion of evaluation without embedding?
On Mar 12, 2019, at 11:44 AM, Giuseppe G. A. Celano celano@informatik.uni-leipzig.de wrote:
let $o := file:create-dir("/Users/mycomputer/prova") let $o2 := file:write("/Users/mycomputer/prova/file1.xml", "ciao") let $o3 := file:write("/Users/mycomputer/prova/file2.xml", file:read-text("/Users/mycomputer/prova/file1.xml")) return ($o, $o2, $o3)
This actually works. In my real example the writing of $o2 requires e few seconds. It might be that $o3 is evaluated while $o2 is still running?
Dr. Giuseppe G. A. Celano DFG-project leader Universität Leipzig Institute of Computer Science, NLP Augustusplatz 10 Tel: +4934132223 04109 Leipzig Deutschland
E-mail: celano@informatik.uni-leipzig.de Web site 1: http://asv.informatik.uni-leipzig.de/en/staff/Giuseppe_Celano Web site 2: https://sites.google.com/site/giuseppegacelano/
On Mar 12, 2019, at 11:27 AM, Michael Seiferle ms@basex.org wrote:
Hi Guiseppe,
The following pattern is supposed to / does work:
file:write("1.txt", "Written to 1.txt"), file:write("2.txt", file:read-text("1.txt")), "Read from 2.txt: " || file:read-text('2.txt')
Could you maybe elaborate a bit more on your code?
Best from Konstanz
Michael
Am 12.03.2019 um 11:19 schrieb Giuseppe G. A. Celano celano@informatik.uni-leipzig.de:
Hi
I wrote a single script which should do: write a file -> open this file -> write another different file. I put the write expressions in the right sequence, but it seems that the second one cannot happen because the file created by the first write function has not yet been created at the time the second function is invoked. Does anyone have a suggestion about this? Thanks.
Best, Giuseppe
Hi Guiseppe,
actually the file-operations are non-deterministic and thus (1) never executed out of order and (2) even executed if you would not return their results ($o, $o2, $o3) and thus might be removed by the compiler. (Christian might correct me if I am wrong ;-))
I came up with the following example that waits 2 seconds before actually writing to $o2:
let $o := file:create-dir("foo") let $o2 := file:write("foo/file1.xml", (function(){ prof:sleep(2000), "Written to File1.xml" })() ) let $o3 := file:write("foo/file2.xml", file:read-text("foo/file1.xml"))
return file:read-text("foo/file2.xml“)
So most probably your example does not fully reflect what’s actually happening — maybe you could provide some more context? If you want to, you may even send your query to me directly so you won’t have disclose it on this mailing list.
Best from Konstanz
Michael
Am 12.03.2019 um 11:44 schrieb Giuseppe G. A. Celano celano@informatik.uni-leipzig.de:
let $o := file:create-dir("/Users/mycomputer/prova") let $o2 := file:write("/Users/mycomputer/prova/file1.xml", "ciao") let $o3 := file:write("/Users/mycomputer/prova/file2.xml", file:read-text("/Users/mycomputer/prova/file1.xml")) return ($o, $o2, $o3)
This actually works. In my real example the writing of $o2 requires e few seconds. It might be that $o3 is evaluated while $o2 is still running?
Dr. Giuseppe G. A. Celano DFG-project leader http://gepris.dfg.de/gepris/projekt/408121292 Universität Leipzig Institute of Computer Science, NLP Augustusplatz 10 Tel: +4934132223 04109 Leipzig Deutschland
E-mail: celano@informatik.uni-leipzig.de mailto:celano@informatik.uni-leipzig.de Web site 1: http://asv.informatik.uni-leipzig.de/en/staff/Giuseppe_Celano http://asv.informatik.uni-leipzig.de/en/staff/Giuseppe_Celano Web site 2: https://sites.google.com/site/giuseppegacelano/ https://sites.google.com/site/giuseppegacelano/
On Mar 12, 2019, at 11:27 AM, Michael Seiferle <ms@basex.org mailto:ms@basex.org> wrote:
Hi Guiseppe,
The following pattern is supposed to / does work:
file:write("1.txt", "Written to 1.txt"), file:write("2.txt", file:read-text("1.txt")), "Read from 2.txt: " || file:read-text('2.txt')
Could you maybe elaborate a bit more on your code?
Best from Konstanz
Michael
Am 12.03.2019 um 11:19 schrieb Giuseppe G. A. Celano <celano@informatik.uni-leipzig.de mailto:celano@informatik.uni-leipzig.de>:
Hi
I wrote a single script which should do: write a file -> open this file -> write another different file. I put the write expressions in the right sequence, but it seems that the second one cannot happen because the file created by the first write function has not yet been created at the time the second function is invoked. Does anyone have a suggestion about this? Thanks.
Best, Giuseppe
basex-talk@mailman.uni-konstanz.de
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Christian Grün -
Giuseppe G. A. Celano -
Michael Seiferle