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Diffstat (limited to 'txr.1')
| -rw-r--r-- | txr.1 | 109 |
1 files changed, 109 insertions, 0 deletions
@@ -25026,6 +25026,83 @@ function produces a copy of from which leading and trailing tabs, spaces and newlines are removed. +.coNP Functions @ string-set-code and @ string-get-code +.synb +.mets (string-set-code < string << value ) +.mets (string-get-code << string ) +.syne +.desc +The +.code string-set-code +and +.code string-get-code +functions provide a mechanism for associating an integer code +with a string. + +Note: this mechanism is the basis for associating system error messages passed +in exceptions with the +.code errno +values of the failed system library calls which precipitated these error +exceptions. + +Not all string types can have an integer code: lazy strings and literal +strings do not have this capability. The +.meta string +argument must be of type +.codn str . + +The +.meta value +argument must be an integer or character. It is recommended that its +value be confined to the non-negative range of the platform's +.code int +C type. Otherwise it is unspecified whether the same value shall be +observed by +.code string-get-code +as what was stored with +.codn string-set-code . + +The +.code string-set-code +function associates the integer +.meta value +with the given +.codn string , +and returns +.codn string . +Any previously associated value is overwritten. + +The +.code string-get-code +function retrieves the value most recently associated with +.metn string . +If +.meta string +has no associated value, then +.code nil +is returned. + +If the +.code string-extend +is invoked on a +.meta string +then it is unspecified whether or not +.meta string +has an associated value and, if so, what value that is, except in the +following case: if +.code string-extend +is invoked with a +.meta final +argument which is true, then +.meta string +is caused not to have an associated value. + +If the +.code string-finish +function is invoked on a +.metn string , +that string is caused not to have an associated value. + .coNP Function @ chrp .synb .mets (chrp << obj ) @@ -47907,6 +47984,38 @@ symbol, either by inheriting directly from .code restart or from an exception subtype of that symbol. +.coNP Treatment of @ errno In Built-in Exceptions +Some \*(TL library functions generate exceptions in response to +conditions arising in the operating system, and those conditions +are associated with a numeric code in the POSIX/ISO C variable +.codn errno . +This code isn't represented as an exception argument. Rather, +in many of these situations, the +.code errno +value is attached to the error message string which is passed +as the first and only exception argument. The value can be +retrieved by using the function +.code string-get-code +on the error message string. If this function returns +.codn nil , +then no such code is available in connection with the given +error. + +.TP* Example: + +.verb +;; the errno value 2 is retrieved from the ser +; + (catch + (open-file "AsDf") + (error (msg) + ;; the value 2 is retrieved from msg + ;; 2 is the common common value of ENOENT + (list (string-get-code msg) msg))) + + -> (2 "error opening \e"AsDf\e": 2/\e"No such file or directory\e"") +.brev + .coNP Functions @, throw @ throwf and @ error .synb .mets (throw < symbol << arg *) |