diff options
| -rw-r--r-- | struct.c | 11 | ||||
| -rw-r--r-- | txr.1 | 8 |
2 files changed, 18 insertions, 1 deletions
@@ -76,7 +76,7 @@ struct struct_inst { val slot[1]; }; -val struct_type_s, meth_s; +val struct_type_s, meth_s, print_s; static cnum struct_id_counter; static val struct_type_hash; @@ -98,6 +98,7 @@ void struct_init(void) convert(val *, 0)); struct_type_s = intern(lit("struct-type"), user_package); meth_s = intern(lit("meth"), user_package); + print_s = intern(lit("print"), user_package); struct_type_hash = make_hash(nil, nil, nil); slot_hash = make_hash(nil, nil, t); struct_type_finalize_f = func_n1(struct_type_finalize); @@ -985,6 +986,14 @@ static void struct_inst_print(val obj, val out, val pretty) num_fast(indent_data)); val save_indent, iter, once; + if (pretty) { + loc ptr = lookup_static_slot_load(st->self, st, print_s); + if (!nullocp(ptr)) { + funcall2(deref(ptr), obj, out); + return; + } + } + put_string(lit("#S("), out); obj_print_impl(st->name, out, pretty); save_indent = inc_indent(out, one); @@ -19280,6 +19280,14 @@ type whose instances have already been inserted as keys in an .code :equal-based hash table, searches for those keys will not work reliably. +.NP* Custom Pretty-Printing + +If a method named by the symbol +.code print +is defined for a structure type, then it is used for pretty-printing instances +of that type. The method takes one argument (in addition to the object), which +specifies the output stream. + .coNP Macro @ defstruct .synb .mets (defstruct >> { name | >> ( name << arg *)} < super |