I use the following to save screen output to a file
writefile("file.txt"),
tex(expression),
closefile()
The above sends the output of the tex() to the file automatically. which is all and well and what I want. (side-point: It also sends an annoying NIL line each time to the file, which I had to parse put later).
Now, when running the above code again, the file is appended to, which is not what I want. I want to either overwrite the file each time, or if there is a way to delete the file, so I can call delete on it before.
I looked at help and not able to find a command to delete a file, and I also see no option to tell writefile() to overwrite the file?
Is there an option or way around this? I am on windows 7, Maxima version: 5.36.1
Lisp: SBCL 1.2.7
I guess you are trying to capture the output of tex into a file. If so, here are a couple of other ways to do it:
tex (expr, destination);
where destination is either a file name (which is appended) or a stream, as created by opena or openw and closed by close. By the way, destination could be false, in which case tex returns a string.
with_stdout (destination, tex (expr));
where again destination is either a file name (which is appended or clobbered, as determined by the global flag file_output_append) or a stream.
with_stdout could be useful if you want to mix in some output not generated by tex, e.g., print("% some commentary");.
Related
Does rails have a way to implement read streams like Node js for file reading?
i.e.
fs.createReadStream(__dirname + '/data.txt');
as apposed to
fs.readFile(__dirname + '/data.txt');
Where I see ruby has
file = File.new("data.txt")
I am unsure of the equivalent in ruby/rails for creating a stream and would like to know if this is possible. The reasons I ask is for memory management as a stream will be delivered piece by piece as apposed to one whole file.
If you want to read a file in Ruby piece-by-piece, there are a host of methods available to you.
IO#each_line/IO::foreach, also implemented in File to iterate over each line of the file. Neither reads the whole file into memory; instead, both simply read up until the next newline, return, and pause reading, barring a possible buffer.
IO#read/IO::read takes a length parameter, which allows you to specify for it to read up to length bytes from the file. This will only read that many, and not the whole thing.
IO::binread does the same as IO::read, but will open the file in binary mode.
IO#readpartial appears to be very similar or identical to IO#read, but is also worth looking at.
IO#getc and IO#gets both read from the file until they reach the end of what they'll return, as far as I can tell.
There are several more that I'm looking for right now.
I'm trying to redirect stdout in Lua (5.1) to a file instead of to console.
There is a third-party API (which I cannot modify) containing a function that prints out a serialized set of data (I do not know which function does the printing, assume some sort of print())
This data is far too verbose to fit on the screen I have to work with (which cannot be scrolled) so I want to have the function's output be directed to a file instead of to console.
I do not have the ability to patch or manipulate Lua versions.
My thought was to change stdout to a file using the poorly documented io.output() file, but this does not seem to work at all.
io.output("foo") -- creates file "foo", should set stdout to "foo"?
print("testing. 1, 2, 3") -- should print into "foo", goes to console instead
Does anyone know of any way to force a functions output into a file, or force all stdout into a file instead of console? TIA.
You need to use io.write method instead of print. It works in a similar way, but doesn't separate parameters with a tab. io.write respects io.output, but print doesn't.
-- save, might need to restore later
real_stdout = io.stdout
file = io.open ('stdout.log', 'w')
io.stdout = file
.... -- call external API
-- restore
io.stdout = real_stdout
I'd like to get a file last modified time in Delphi.
Normally something like FileAge() would do the trick, only the problem is: if I overwrite *File A* with File B using CopyFile, File A's modified date is not updated with current overwrite time as it should(?)
I get that: CopyFile also copy file attributes, but I really need to get the modified date that also works when a file is overwritten.
Is there such function? My whole application relies on modification time to decide whether or not I should proceed with files!
EDIT Just to clarify: I'm only monitoring the files. It's not my application who's modifying them.
The documentation for CopyFile says:
File attributes for the existing file are copied to the new file.
Which means that you cannot use base your program on the last modified attribute of the file, or indeed any attribute of the file. Indeed there are all sorts of ways for the last modified attribute of the file to change. It can in fact go backwards in time.
Instead I suggest that you use ReadDirectoryChangesW to keep track of modifications. That will allow you to receive notifications whenever a file is modified. You can write your program in an event based manner based on the ReadDirectoryChangesW API.
If you can't use ReadDirectoryChangesW and the file attributes, then you'll have to base your decisions on the contents of the file.
I have a spreadsheet that has a list of video filenames in one column.
I'd like for a video player to open when I click on a filename.
Is there a simple way to do this?
There's a hack that lets you call external applications using the HYPERLINK command:
=HYPERLINK("mplayer", "foo")
This opens up mplayer (or whatever you tell it to). However, if I try to pass a command-line argument to the executable using:
=HYPERLINK("mplayer ~/Desktop/foo.mpeg", "foo")
then I get the error: "OpenOffice could not find a web browser on your system". It's probably attempting to parse the first argument and tripping over a space.
Does anybody know of a way I can achieve what I want? Perhaps there's a way to do this with macros?
The list of filenames is auto-generated (hundreds) so I don't want to do anything manual.
You might try using %20 instead of the space, though I don't expect it to work.
Does your player have anything like a play-list provision? It seems that it would be more direct to compile a play list in whatever format that is, than attempt to force HYPERLINK( ) to work here.
The other possibiity is to see if there is a URL scheme registered on your system that will invoke the player, rather than a command line. Or just use the file: scheme and see if you can launch the mpeg that way. You may have to monkey with the file path to get it right. You may also have to %-escape the '~' if you have any of those.
My program accepts input file names either as command line parameters or in a drag and drop operation or in Explorer by clicking on filenames with an extension that is associated with my program.
The command line and drag and drop work fine, but it is clicking on the filenames in Explorer that causes problems when the filepaths of the files clicked on have spaces in them, e.g.:
c:\temp\file one.txt
c:\my directory\filetwo.txt
c:\my directory\file three.txt
then, the ParamStr function gives me back:
ParamStr(1): c:\temp\file
ParamStr(2): one.txt
ParamStr(3): c:\my
ParamStr(4): directory\filetwo.txt
ParamStr(5): c:\my
ParamStr(6): directory\file
ParamStr(7): three.txt
How can I best reconstitute these back into the three filenames that I need?
It might be your shell file association that does not include the pair of "".
Like these ones for opening:
"C:\Program Files\WinRAR\WinRAR.exe" "%1"
or with DDE message:
[open("%1")]
Command-line parameters with spaces in them, such as filenames, should be quoted. This makes the param parser realize that it's supposed to keep them together. If the user's not quoting the filename, it's operator error.
If a drag-and-drop system is doing this, on the other hand, then you've got a bug in your drag-and-drop library and you need to talk to whoever created it. I'm a bit confused, though, as to why drag-and-drop operations are messing with ParamStr. That should only be set by the params passed to your program at the moment it's invoked, not once it's up and running. Maybe I'm missing something?
i use the CmdLineHelper unit, from here.