P.S. In your case, you'll probably just use (current-command-line-arguments) to get the value.
If your program uses many command line arguments, you may prefer using `command-line': http://docs.racket-lang.org/reference/Command-Line_Parsing.html. On Mon, Aug 20, 2012 at 8:40 AM, Greg Hendershott <greghendersh...@gmail.com> wrote: > Racket has the idea of `parameters'. By convention, these are named > current-xyz. Examples include current-input-port, current-output-port, > and current-command-line-arguments. > > Parameters are functions you can call to set or get a value. To get > the current value, call with no arguments. To set, call with the new > value. (That's why you're seeing the function documented both ways.) > > Parameters are an alternative to using a global variable and `set!'. > There is a `parameterize' form to make it easier to temporarily change > the value and have it restored. Also they are per thread. > > Parameters are described here: > http://docs.racket-lang.org/guide/parameterize.html > > On Mon, Aug 20, 2012 at 3:00 AM, Rouben Rostamian <rostam...@umbc.edu> wrote: >> Oh, the use of (current-command-line-arguments) is a terrific >> idea and a great improvement over what I was trying to do. >> Thanks for pointing it out. >> >> This brings me to a tangentially related question. >> >> I am using Racket v5.1.3. Searching the manuals for >> current-command-line-arguments leads to the following: >> >> | (current-command-line-arguments) >> | -> (vectorof (and/c string? immutable?)) >> | >> | (current-command-line-arguments argv) -> void? >> | argv : (vectorof (and/c string? immutable?)) >> | >> | A parameter that is initialized with command-line arguments >> | when Racket starts (not including any command-line arguments >> | that were treated as flags for the system). >> >> That's all it says. I understand the first form: it says >> (current-command-line-arguments) returns the command-line >> arguments in a vector. I don't understand the second form. >> What is (current-command-line-arguments argv) supposed to do? >> >> -- Rouben >> >> On Mon, Aug 20, 2012 at 07:50:00AM +0200, Rüdiger Asche wrote: >>> >>> Do you need to run echo.rkt under control of racket? If you compile >>> it as a standalone, you can use >>> >>> (current-command-line-arguments) >>> >>> within echo.rkt to access the vector or command line arguments. >>> >>> ----- Original Message ----- From: "Rouben Rostamian" >>> <rostam...@umbc.edu> >>> To: <users@racket-lang.org> >>> Sent: Monday, August 20, 2012 12:42 AM >>> Subject: [racket] Need help with running racket from the command-line >>> >>> >>> >I am having difficulty in interpreting Racket's command-line >>> >options described in the User Guide. Please help if you can. >>> > >>> >I want to do something like this: >>> > >>> > racket -t echo.rkt -e '(echo "hi")' >>> > >>> >The file echo.rkt (which is given at the end of this message) >>> >is a module that provides a function "echo" which simply prints >>> >its argument to the terminal. >>> > >>> >I expect the Unix command >>> > >>> > racket -t echo.rkt -e '(echo "hi")' >>> > >>> >to print "hi" to the terminal and exit. But it doesn't; it complains >>> >about an unbound identifier. This is Racket v5.1.3, if it matters. >>> > >>> >Here is the content of the file echo.rkt: >>> > >>> >;; echo.rkt ------------ >>> > >>> >#lang racket >>> > >>> >(provide echo) >>> > >>> >(define (echo x) >>> > (display x) >>> > (newline)) >>> > >>> >;; end of echo.rkt ----- >>> > >>> > >>> >-- >>> >Rouben Rostamian >> ____________________ >> Racket Users list: >> http://lists.racket-lang.org/users ____________________ Racket Users list: http://lists.racket-lang.org/users
