Reading a file in one sweep
Sometimes it is useful to read a file into memory in one go. For that we have the word f:slurp.This word creates a buffer instead of a string! This means that is not the best way for reading a text file, if only because it can consume lots of memory. For a text file we’d better use f:eachline as in this example:
OS level file write operations invoked by 8th
f:chmod
Most often used to change the read-only mode of the file; on Unix-like OSes can do many more things.
f:copy
Tries to copy a file.
f:copydir
Tries to (recursively) copy a whole directory.
f:link
Tries to create a symbolic link to a file. This feature is mostly used in Unix like OS-es.
f:mkdir
Tries to create a new directory.
OS level file info requests
f:canwrite?Detects if it is possible to write to a given file.
f:ctime
Gets creation time of a file.
Read the manual
When I go through the manual for the f namespace I see a lot of very useful words.So really, you should study the manual, otherwise you’ll miss the juicy parts of 8th
A final example of file handling
We will:1. Go into the root directory c:\ (Windows here)
2. Check if a directory with the name example already exists there
3. If not, create it
4. Go into that directory
5. Create a small text file there
6. Query some file info of that file
Program source code
"example" var, dirName
"test.txt" var, fileName
false var, dirExists
["line 1\n", "line 2\n", "line 3\n"] var, records
: chkSubdir
dirName @ f:exists?
if
"The name already exists and ..." . cr
dirName @ f:dir?
if
true dirExists !
"... it is indeed a directory!" . cr
else
"Error: a file with that name exists already!"
. cr reset bye
then
else
"The directory does not exist yet ..." . cr
then
;
: makeDir
dirExists @ not
if
"... so we create it now!" . cr
dirName @ f:mkdir not
if
"Error: cannot create directory!" .
cr reset bye
then
then
;
: openFile
fileName @ f:create dup \ dup to retain file handle
null?
if
"Error: error while creating file!" .
cr reset bye
then
;
: helpWrite
\ Stack: file ix value
swap \ Stack: file value ix
drop \ Stack: file value
f:write \ Stack: file rc
null? if "Error: writing to file!" . cr reset bye then
\ Stack: file
;
: writeFile
records @ ' helpWrite a:each
drop \ Get rid of array now
;
: openro
fileName @ f:open-ro
dup null? \ dup to retain file handle
if
"Error: error while reopening file!" . cr reset bye
then
;
: queryFile
getcwd "Current directory is: " . . cr
fileName @ f:exists?
if
"The file does indeed exist now!" . cr
else
"Error: file not found!" . cr reset bye
then
openro
f:size "File size : " . . " bytes" . cr
f:ctime "File created at : " . . cr
f:mtime "File modified at: " . . cr
f:close
;
: app:main
"c:\\" chdir \ Set current directory to c:\
chkSubdir \ Does the subdirectory exist?
makeDir \ If not, create it!
dirName @ chdir \ Set current directory
openFile \ Open a file for output
writeFile \ Write the records to the file
f:close \ Close the output file
openro \ Open written file for read
queryFile \ Now query some file specs
bye
;
Below the output of two consecutive runs:
More info about 8th
8th Website: http://8th-dev.com
8th Forum: http://8th-dev.com/forum
My YouTube Channel: https://goo.gl/DscYVD
The Big 8th Lessons Book: http://goo.gl/qDa6fH
