I have the following Makefile:
X=a.jar b.jar c.jar
Y=/var/tmp/abc/a.jar /var/tmp/abc/b.jar /var/tmp/abc/c.jar
all: $(addprefix /var/tmp/abc/tmp/, $(X))
define AddRule
dst=$1
src=$2
/var/tmp/abc/tmp/$(dst): $(src)
#echo $$#
#echo $$^
#mkdir -p $$(dir $$#)
#cp $$^ $$#
endef
$(foreach jar, $(X), $(eval $(call AddRule, $(jar), $(filter %$(jar), $(Y)))))
(/var/tmp/abc/{a,b,c}.jar exist)
Basically, for each file name in $X, I want to find the full path in $Y and create a rule that copies that file to /var/tmp/abc/tmp (I know there's a much easier way to do this, but my actual Makefile is more complicated and needs a construct like this).
When I run this Makefile, I get the following output:
/var/tmp/abc/tmp/a.jar
/var/tmp/abc/a.jar
/var/tmp/abc/tmp/b.jar
/var/tmp/abc/b.jar
make: *** No rule to make target `/var/tmp/abc/tmp/c.jar', needed by `all'. Stop.
Now the "funny" part: If I add the following line after declaring the "all" rule:
X+=d
all three jar files are processed, 'make' doesn't mention anything about 'd' (even if file 'd' doesn't exist), and the run is a success.
So it looks like the foreach loop doesn't go through the last iteration (or most probably something else that leads to the same results happens). Does anybody know what the problem is and how to fix it?
Thanks!
It's not just the last iteration of the loop that's bad. Basically call expands $(dst) to whatever value it has when call is invoked, not when the new code is evaluated. Then the new code is evaluated, and then in the next iteration the definition is expanded-- with the values that have been set by the previous block of new code. So instead of {a, b, c} it gives { , a, b} (you have to stare at this for a while before it makes sense).
Solution: put in a couple of extra $s:
define AddRule
dst=$1
src=$2
/var/tmp/abc/tmp/$$(dst): $$(src)
...
endef
Related
I'm trying to add helpful messages for arbitrary builds. If the build fails the user can, for example, install the package with different arguments.
My interface idea is to provide a function, build-with-message, that would be called with something like this:
build-with-message
''Building ${pkg.name}. Alternative invocations are: ..''
pkg
My implementation is based on builtins.seq
build-with-message = msg : pkg :
seq
(self.runCommand "issue-message" {} ''mkdir $out; echo ${msg}'')
pkg;
When I build a package with build-with-message I never see the message. My hunch is that seq evaluates the runCommand far enough to see that a set is returned and moves on to building the package. I tried with deepSeq as well, but a deepSeq build fails on runCommand. I also tried calling out some attributes from the runCommand, e.g.
(self.runCommand "issue-message" {} ''mkdir $out; echo ${msg}'').drvPath
(self.runCommand "issue-message" {} ''mkdir $out; echo ${msg}'').out
My thought being that calling for one of these would prompt the rest of the build. Perhaps I'm not calling the right attribute, but in any case the ones I've tried don't work.
So:
Is there a way to force the runCommand to build in the above scenario?
Is there already some builtin that just lets me issue messages on top of arbitrary builds?
Here's me answering my own question again, consider this a warning.
Solution:
I've in-lined some numbered comments to help with the explanation.
build-with-message = msg : pkg :
let runMsg /*1*/ = self.runCommand "issue-message"
{ version = toString currentTime; /*2*/ } ''
cat <<EOF
${msg}
EOF
echo 0 > $out /*3*/
'';
in seq (import runMsg /*4*/) pkg; /*5*/
Explanation:
runMsg is the derivation that issues the message.
Adding a version based on the current time ensures that the build of runMsg will not be in /nix/store. Otherwise, each unique message will only be issued for the first build.
After the message is printed, a 0 is saved to file as the output of the derivation.
The import loads runMsg--a derivation, and therefore serialized as the path $out. Import expects a nix expression, which in this case is just the number 0 (a valid nix expression).
Now, since the runMsg output will not be available until after it has been built, the seq command will build it (issuing the message) and then build pkg.
Discussion:
I take note of Robert Hensing's comment to my question--this may not be something Nix was not intended for. I'm not arguing against that. Moving on.
Notice that issuing a message like so will add a file to your nix store for every message issued. I don't know if the message build will be garbage collected while pkg is still installed, so there's the possibility of polluting the nix store if such a pattern is overused.
I also think it's really interesting that the result of the runMsg build was to install a nix expression. I suppose this opens the door to doing useful things.
Ideally, I'd like a list of output files for a target without building. I imagine this should be possible using cquery which runs post-analysis, but can't figure out how.
Here's my output.cquery
def format(target):
outputs = target.files.to_list()
return outputs[0].path if len(outputs) > 0 else "(missing)"
You can run this as follows:
bazel cquery //a/b:bundle --output starlark \
--starlark:file=output.cquery 2>/dev/null
bazel-out/darwin-fastbuild/bin/a/b/something-bundle.zip
For more information on cquery.
What exactly do you mean by "output files" here? Do you mean that you'd like to know the files generated if you build the target on the command line?
At what point would you like to have this information? Do you really want to invoke a bazel query command to acquire this information, or would you like it during analysis? I don't think there's a way, using bazel query, to get the exact expected absolute path of output files (or even the workspace-relative path, for example, bazel-out/foo/bar/baz.txt)
It may be a bit more involved than you want, but Requesting Output Files
has some information about specifying output files in Starlark, with a brief bit about acquiring information about your dependencies' output files (See DefaultInfo
I made a slight improvement to Engene's answer, since a target's output might be multiple:
bazel cquery --output=starlark \
--starlark:expr="'\n'.join([f.path for f in target.files.to_list()])" \
//foo:bar
In my Informix 4GL program, I have an input field where the user can insert a URL and the feed is later being sent over to the web via a script.
How can I validate the URL at the time of input, to ensure that it's a live link? Can I make a call and see if I get back any errors?
I4GL checking the URL
There is no built-in function to do that (URLs didn't exist when I4GL was invented, amongst other things).
If you can devise a C method to do that, you can arrange to call that method through the C interface. You'll write the method in native C, and then write an I4GL-callable C interface function using the normal rules. When you build the program with I4GL c-code, you'll link the extra C functions too. If you build the program with I4GL-RDS (p-code), you'll need to build a custom runner with the extra function(s) exposed. All of this is standard technique for I4GL.
In general terms, the C interface code you'll need will look vaguely like this:
#include <fglsys.h>
// Standard interface for I4GL-callable C functions
extern int i4gl_validate_url(int nargs);
// Using obsolescent interface functions
int i4gl_validate_url(int nargs)
{
if (nargs != 1)
fgl_fatal(__FILE__, __LINE__, -1318);
char url[4096];
popstring(url, sizeof(url));
int r = validate_url(url); // Your C function
retint(r);
return 1;
}
You can and should check the manuals but that code, using the 'old style' function names, should compile correctly. The code can be called in I4GL like this:
DEFINE url CHAR(256)
DEFINE rc INTEGER
LET url = "http://www.google.com/"
LET rc = i4gl_validate_url(url)
IF rc != 0 THEN
ERROR "Invalid URL"
ELSE
MESSAGE "URL is OK"
END IF
Or along those general lines. Exactly what values you return depends on your decisions about how to return a status from validate_url(). If need so be, you can return multiple values from the interface function (e.g. error number and text of error message). Etc. This is about the simplest possible design for calling some C code to validate a URL from within an I4GL program.
Modern C interface functions
The function names in the interface library were all changed in the mid-00's, though the old names still exist as macros. The old names were:
popstring(char *buffer, int buflen)
retint(int retval)
fgl_fatal(const char *file, int line, int errnum)
You can find the revised documentation at IBM Informix 4GL v7.50.xC3: Publication library in PDF in the 4GL Reference Manual, and you need Appendix C "Using C with IBM Informix 4GL".
The new names start ibm_lib4gl_:
ibm_libi4gl_popMInt()
ibm_libi4gl_popString()
As to the error reporting function, there is one — it exists — but I don't have access to documentation for it any more. It'll be in the fglsys.h header. It takes an error number as one argument; there's the file name and a line number as the other arguments. And it will, presumably, be ibm_lib4gl_… and there'll be probably be Fatal or perhaps fatal (or maybe Err or err) in the rest of the name.
I4GL running a script that checks the URL
Wouldn't it be easier to write a shell script to get the status code? That might work if I can return the status code or any existing results back to the program into a variable? Can I do that?
Quite possibly. If you want the contents of the URL as a string, though, you'll might end up wanting to call C. It is certainly worth thinking about whether calling a shell script from within I4GL is doable. If so, it will be a lot simpler (RUN "script", IIRC, where the literal string would probably be replaced by a built-up string containing the command and the URL). I believe there are file I/O functions in I4GL now, too, so if you can get the script to write a file (trivial), you can read the data from the file without needing custom C. For a long time, you needed custom C to do that.
I just need to validate the URL before storing it into the database. I was thinking about:
#!/bin/bash
read -p "URL to check: " url
if curl --output /dev/null --silent --head --fail "$url"; then
printf '%s\n' "$url exist"
else
printf '%s\n' "$url does not exist"
fi
but I just need the output instead of /dev/null to be into a variable. I believe the only option is to dump the output into a temp file and read from there.
Instead of having I4GL run the code to validate the URL, have I4GL run a script to validate the URL. Use the exit status of the script and dump the output of curl into /dev/null.
FUNCTION check_url(url)
DEFINE url VARCHAR(255)
DEFINE command_line VARCHAR(255)
DEFINE exit_status INTEGER
LET command_line = "check_url ", url
RUN command_line RETURNING exit_status
RETURN exit_status
END FUNCTION {check_url}
Your calling code can analyze exit_status to see whether it worked. A value of 0 indicates success; non-zero indicates a problem of some sort, which can be deemed 'URL does not work'.
Make sure the check_url script (a) exits with status zero on success and non-zero on any sort of failure, and (b) doesn't write anything to standard output (or standard error) by default. The writing to standard error or output will screw up screen layouts, etc, and you do not want that. (You can obviously have options to the script that enable standard output, or you can invoke the script with options to suppress standard output and standard error, or redirect the outputs to /dev/null; however, when used by the I4GL program, it should be silent.)
Your 'script' (check_url) could be as simple as:
#!/bin/bash
exec curl --output /dev/null --silent --head --fail "${1:-http://www.example.com/"
This passes the first argument to curl, or the non-existent example.com URL if no argument is given, and replaces itself with curl, which generates a zero/non-zero exit status as required. You might add 2>/dev/null to the end of the command line to ensure that error messages are not seen. (Note that it will be hell debugging this if anything goes wrong; make sure you've got provision for debugging.)
The exec is a minor optimization; you could omit it with almost no difference in result. (I could devise a scheme that would probably spot the difference; it involves signalling the curl process, though — kill -9 9999 or similar, where the 9999 is the PID of the curl process — and isn't of practical significance.)
Given that the script is just one line of code that invokes another program, it would be possible to embed all that in the I4GL program. However, having an external shell script (or Perl script, or …) has merits of flexibility; you can edit it to log attempts, for example, without changing the I4GL code at all. One more file to distribute, but better flexibility — keep a separate script, even though it could all be embedded in the I4GL.
As Jonathan said "URLs didn't exist when I4GL was invented, amongst other things". What you will find is that the products that have grown to superceed Informix-4gl such as FourJs Genero will cater for new technologies and other things invented after I4GL.
Using FourJs Genero, the code below will do what you are after using the Informix 4gl syntax you are familiar with
IMPORT com
MAIN
-- Should succeed and display 1
DISPLAY validate_url("http://www.google.com")
DISPLAY validate_url("http://www.4js.com/online_documentation/fjs-fgl-manual-html/index.html#c_fgl_nf.html") -- link to some of the features added to I4GL by Genero
-- Should fail and display 0
DISPLAY validate_url("http://www.google.com/testing")
DISPLAY validate_url("http://www.google2.com")
END MAIN
FUNCTION validate_url(url)
DEFINE url STRING
DEFINE req com.HttpRequest
DEFINE resp com.HttpResponse
-- Returns TRUE if http request to a URL returns 200
TRY
LET req = com.HttpRequest.create(url)
CALL req.doRequest()
LET resp = req.getResponse()
IF resp.getStatusCode() = 200 THEN
RETURN TRUE
END IF
-- May want to handle other HTTP status codes
CATCH
-- May want to capture case if not connected to internet etc
END TRY
RETURN FALSE
END FUNCTION
I have a batchfile which I use for managing the translation of various programs.
Now I want a delphi application to call this batchfile and pass on the parameter it needs for further processing. Unfortunately the parameters contain spaces which leads to a splitup. Is there a way to keep all parameters tied up as intended?
this is how my batchfile looks:
ECHO Scan for new ressources
%MLDIR%\Ml7Build.exe s %1%
ECHO Import glossary for new translation
%MLDIR%\MlBuild.exe i %2%
ECHO Create translated application
%MLDIR%\Ml7Build.exe b %3%
I tried to use the ShellExecute-Command from ShellApi because I found several similar questions on SO, but none of them could help me in solving my problem. My delphi code looks like this:
param1 := ExtractFileName(hMLProj);
param2 := '-f: '+MLWorkDir+'Prev_'+ExtractFileName(hMLProj)+' -settings:Auftrag_Test.importsettings-method:2 -overwri:3 -error:2 '+ExtractFileName(hMLProj)+' ';
param3 := ExtractFileName(hMLProj);
ShellExecute(0,'open',PCHAR(MLWorkDir+'__AutomatedTranslationFUBAR.bat'),PChar(param1 +param2 +param3),nil,SW_SHOWDEFAULT);
ECHO Scan for new resources
%MLDIR%\Ml7Build.exe s %~1
ECHO Import glossary for new translation
%MLDIR%\MlBuild.exe i %~2
REM is 7 ^ omitted here?
ECHO Create translated application
%MLDIR%\Ml7Build.exe b %~3
Note that %n not %n% (n=1..9) refers to the parameter n supplied to the batch. The tilde removes "any enclosing quotes."
Parameters require to be "enclosed in quotes" (and they must be double-quotes) if they contain separators such as spaces.
I have embedded lua and I want precompile my script. For that, I call the main of luac (with argc the number of file is 1). My problem is on the function doargs of luac. I don't understand the use of the variable i. Because when I use one script. The result of i after the doargs function is 1. And in the main function we have argc -= i after. And so argc = 0 and I have a error "no file". Any idea ?
luac is meant to be a command line utility for compiling .lua files. This expected usage is the reason why you're getting an error.
When you start an executable the OS passes the name of the program as its first argument (argv[0]). The luac main function assumes it is being called by the OS, so it expects that there will always be at least one argument and its argv[0] will be the name of the executable.
For this reason doargs starts its for loop at 1 and will always ignore that first (0th) argument. It returns how many options it has processed, which is also the offset of the first filename in the argv array. The main function uses this to know where the list of files starts.
If you really want to use the main function to precompile your scripts, then supply an extra dummy argument at the beginning of your argument array and list your files after that. Preferably you should use luac from the command line and supply an output file where the precompiled script will be stored like this:
luac -o outputFile script.lua
Alternatively, take a look at chapter 8 of Programming in Lua (Compilation, Execution, and Errors) for a pure Lua solution, or the the luaL_dofile, luaL_dostring, lua_dump, and lua_load functions in the Reference Manual for a C API solution.