diff options
Diffstat (limited to 'txr.1')
| -rw-r--r-- | txr.1 | 33 |
1 files changed, 27 insertions, 6 deletions
@@ -10388,20 +10388,22 @@ followed by a nested list syntax denotes a struct literal. The first item in the syntax is a symbol denoting the struct type name. This must be the name of a struct type, otherwise the literal is erroneous. Followed by the struct type are slot names -interleaved with their values. Each slot name which is present in the +interleaved with their values. The values are literal expressions, +not subject to evaluation. +Each slot name which is present in the literal must name a slot in the struct type, though not all slots in the struct type must be present in the literal. + When a struct literal is read, the denoted struct type is constructed as if by a call to .code make-struct -whose +with an empty .meta plist -argument is formed from the +argument, followed by a sequence of assignments which store into each .meta slot -and +the corresponding .meta value -elements of the literal, individually quoted to suppress their -evaluation as forms. +expression. .NP* Hash Literals @@ -47305,6 +47307,25 @@ of these version values, the described behaviors are provided if is given an argument which is equal or lower. For instance .code "-C 103" selects the behaviors described below for version 105, but not those for 102. +.IP 154 +After version 154, changes were introduced in the semantics of struct +literals. Previously, the syntax +.code "#S(abc x a y b)" +denoted the construction of an instance of +.code abc +with +.code "x a y b" +as the constructor parameters, similarly to +.codn "(new abc x 'a y 'b)" . +The new behavior is that +.code abc +is constructed using no parameters, as if by +.code "(new abc)" +and then the slot values are assigned. This means that the values +specified in the literal override any manipulations of those slots by +the type's user-defined +.code :postinit +handlers. .IP 151 After version 151, changes were implemented to the way static slots work in \*(TL structs. Selecting compatibility with 151 restores most of the behaviors. |