1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
|
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"
"http://www.w3.org/TR/REC-html40/loose.dtd">
<HTML>
<HEAD>
<META http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<META name="GENERATOR" content="hevea 1.08">
<LINK rel="stylesheet" type="text/css" href="gprolog.css">
<TITLE>
Predicate information
</TITLE>
</HEAD>
<BODY TEXT=black BGCOLOR=white>
<A HREF="gprolog030.html"><IMG SRC ="previous_motif.gif" ALT="Previous"></A>
<A HREF="gprolog023.html"><IMG SRC ="contents_motif.gif" ALT="Up"></A>
<A HREF="gprolog032.html"><IMG SRC ="next_motif.gif" ALT="Next"></A>
<HR>
<H3 CLASS="subsection"><A NAME="htoc98">7.8</A> Predicate information</H3><UL>
<LI><A HREF="gprolog031.html#toc69"><TT>current_predicate/1</TT></A>
<LI><A HREF="gprolog031.html#toc70"><TT>predicate_property/2</TT></A>
</UL>
<A NAME="toc69"></A>
<H4 CLASS="subsubsection"><A NAME="htoc99">7.8.1</A> <TT>current_predicate/1</TT></H4>
<A NAME="current-predicate/1"></A>
<B>Templates</B>
<DL CLASS="list" COMPACT="compact"><DT CLASS="dt-list"><DD CLASS="dd-list"><TT>
current_predicate(?predicate_indicator)</TT></DL>
<B>Description</B><BR>
<BR>
<TT>current_predicate(Pred)</TT> succeeds if there
exists a predicate indicator of a defined procedure that unifies with
<TT>Pred</TT>. All user defined procedures are found, whether static or
dynamic. Internal system procedures whose name begins
with <TT>'$'</TT> are not found. A user-defined procedure is found
even when it has no clauses. A user-defined procedure is not found if
it has been abolished. To conform to the ISO reference, built-in predicates
are not found except if the <TT>strict_iso</TT> Prolog flag is switched off (section <A HREF="gprolog045.html#set-prolog-flag/2">7.22.1</A>). This predicate is re-executable on
backtracking.<BR>
<BR>
<B>Errors</B><BR>
<TABLE CELLSPACING=2 CELLPADDING=0>
<TR><TD BGCOLOR=black COLSPAN=3><TABLE BORDER=0 WIDTH="100%" CELLSPACING=0 CELLPADDING=1><TR><TD></TD></TR></TABLE></TD>
</TR>
<TR><TD VALIGN=top ALIGN=left><TT>Pred</TT> is neither a variable nor a predicate indicator</TD>
<TD VALIGN=top ALIGN=center NOWRAP> </TD>
<TD VALIGN=top ALIGN=left><TT>type_error(predicate_indicator, Pred)</TT></TD>
</TR>
<TR><TD BGCOLOR=black COLSPAN=3><TABLE BORDER=0 WIDTH="100%" CELLSPACING=0 CELLPADDING=1><TR><TD></TD></TR></TABLE></TD>
</TR>
<TR><TD VALIGN=top ALIGN=left><TT>Pred</TT> is a term <TT>Name/Arity</TT> and <TT>Arity</TT> is
neither a variable nor an integer</TD>
<TD VALIGN=top ALIGN=center NOWRAP> </TD>
<TD VALIGN=top ALIGN=left><TT>type_error(integer, Arity)</TT></TD>
</TR>
<TR><TD BGCOLOR=black COLSPAN=3><TABLE BORDER=0 WIDTH="100%" CELLSPACING=0 CELLPADDING=1><TR><TD></TD></TR></TABLE></TD>
</TR>
<TR><TD VALIGN=top ALIGN=left><TT>Pred</TT> is a term <TT>Name/Arity</TT> and <TT>Name</TT> is
neither a variable nor an atom</TD>
<TD VALIGN=top ALIGN=center NOWRAP> </TD>
<TD VALIGN=top ALIGN=left><TT>type_error(atom, Name)</TT></TD>
</TR>
<TR><TD BGCOLOR=black COLSPAN=3><TABLE BORDER=0 WIDTH="100%" CELLSPACING=0 CELLPADDING=1><TR><TD></TD></TR></TABLE></TD>
</TR>
<TR><TD VALIGN=top ALIGN=left><TT>Pred</TT> is a term <TT>Name/Arity</TT> and <TT>Arity</TT> is
an integer < 0</TD>
<TD VALIGN=top ALIGN=center NOWRAP> </TD>
<TD VALIGN=top ALIGN=left><TT>domain_error(not_less_than_zero, Arity)</TT></TD>
</TR>
<TR><TD BGCOLOR=black COLSPAN=3><TABLE BORDER=0 WIDTH="100%" CELLSPACING=0 CELLPADDING=1><TR><TD></TD></TR></TABLE></TD>
</TR>
<TR><TD VALIGN=top ALIGN=left><TT>Pred</TT> is a term <TT>Name/Arity</TT> and <TT>Arity</TT> is
an integer > <TT>max_arity</TT> flag (section <A HREF="gprolog045.html#set-prolog-flag/2">7.22.1</A>)</TD>
<TD VALIGN=top ALIGN=center NOWRAP> </TD>
<TD VALIGN=top ALIGN=left><TT>representation_error(max_arity)</TT></TD>
</TR>
<TR><TD BGCOLOR=black COLSPAN=3><TABLE BORDER=0 WIDTH="100%" CELLSPACING=0 CELLPADDING=1><TR><TD></TD></TR></TABLE></TD>
</TR></TABLE><BR>
<B>Portability</B><BR>
<BR>
ISO predicate.<BR>
<BR>
<A NAME="toc70"></A>
<H4 CLASS="subsubsection"><A NAME="htoc100">7.8.2</A> <TT>predicate_property/2</TT></H4>
<A NAME="predicate-property/2"></A>
<B>Templates</B>
<DL CLASS="list" COMPACT="compact"><DT CLASS="dt-list"><DD CLASS="dd-list"><TT>
predicate_property(?predicate_indicator, ?predicate_property)</TT></DL>
<B>Description</B><BR>
<BR>
<TT>predicate_property(Pred, Property)</TT> succeeds if there
exists a predicate indicator of a defined procedure that unifies with
<TT>Pred</TT> and if <TT>Property</TT> unifies with one of the properties of
the procedure. All user defined procedures and built-in predicates are
found. Internal system procedures whose name begins with <TT>'$'</TT>
are not found. This predicate is re-executable on backtracking.<BR>
<BR>
<B>Predicate properties</B>:
<UL CLASS="itemize"><LI CLASS="li-itemize"><TT>static</TT>: if the procedure is static.<BR>
<BR>
<LI CLASS="li-itemize"><TT>dynamic</TT>: if the procedure is dynamic.<BR>
<BR>
<LI CLASS="li-itemize"><TT>private</TT>: if the procedure is private.<BR>
<BR>
<LI CLASS="li-itemize"><TT>public</TT>: if the procedure is public.<BR>
<BR>
<LI CLASS="li-itemize"><TT>user</TT>: if the procedure is a user-defined procedure.<BR>
<BR>
<LI CLASS="li-itemize"><TT>built_in</TT>: if the procedure is a Prolog built-in predicate.<BR>
<BR>
<LI CLASS="li-itemize"><TT>built_in_fd</TT>: if the procedure is an FD built-in predicate.<BR>
<BR>
<LI CLASS="li-itemize"><TT>native_code</TT>: if the procedure is compiled in native code.<BR>
<BR>
<LI CLASS="li-itemize"><TT>prolog_file(File)</TT>: source file from which the
predicate has been read.<BR>
<BR>
<LI CLASS="li-itemize"><TT>prolog_line(Line)</TT>: line number of the source
file.</UL>
<B>Errors</B><BR>
<TABLE CELLSPACING=2 CELLPADDING=0>
<TR><TD BGCOLOR=black COLSPAN=3><TABLE BORDER=0 WIDTH="100%" CELLSPACING=0 CELLPADDING=1><TR><TD></TD></TR></TABLE></TD>
</TR>
<TR><TD VALIGN=top ALIGN=left><TT>Pred</TT> is neither a variable nor a predicate indicator</TD>
<TD VALIGN=top ALIGN=center NOWRAP> </TD>
<TD VALIGN=top ALIGN=left><TT>type_error(predicate_indicator, Pred)</TT></TD>
</TR>
<TR><TD BGCOLOR=black COLSPAN=3><TABLE BORDER=0 WIDTH="100%" CELLSPACING=0 CELLPADDING=1><TR><TD></TD></TR></TABLE></TD>
</TR>
<TR><TD VALIGN=top ALIGN=left><TT>Pred</TT> is a term <TT>Name/Arity</TT> and <TT>Arity</TT> is
neither a variable nor an integer</TD>
<TD VALIGN=top ALIGN=center NOWRAP> </TD>
<TD VALIGN=top ALIGN=left><TT>type_error(integer, Arity)</TT></TD>
</TR>
<TR><TD BGCOLOR=black COLSPAN=3><TABLE BORDER=0 WIDTH="100%" CELLSPACING=0 CELLPADDING=1><TR><TD></TD></TR></TABLE></TD>
</TR>
<TR><TD VALIGN=top ALIGN=left><TT>Pred</TT> is a term <TT>Name/Arity</TT> and <TT>Name</TT> is
neither a variable nor an atom</TD>
<TD VALIGN=top ALIGN=center NOWRAP> </TD>
<TD VALIGN=top ALIGN=left><TT>type_error(atom, Name)</TT></TD>
</TR>
<TR><TD BGCOLOR=black COLSPAN=3><TABLE BORDER=0 WIDTH="100%" CELLSPACING=0 CELLPADDING=1><TR><TD></TD></TR></TABLE></TD>
</TR>
<TR><TD VALIGN=top ALIGN=left><TT>Pred</TT> is a term <TT>Name/Arity</TT> and <TT>Arity</TT> is
an integer < 0</TD>
<TD VALIGN=top ALIGN=center NOWRAP> </TD>
<TD VALIGN=top ALIGN=left><TT>domain_error(not_less_than_zero, Arity)</TT></TD>
</TR>
<TR><TD BGCOLOR=black COLSPAN=3><TABLE BORDER=0 WIDTH="100%" CELLSPACING=0 CELLPADDING=1><TR><TD></TD></TR></TABLE></TD>
</TR>
<TR><TD VALIGN=top ALIGN=left><TT>Pred</TT> is a term <TT>Name/Arity</TT> and <TT>Arity</TT> is
an integer > <TT>max_arity</TT> flag (section <A HREF="gprolog045.html#set-prolog-flag/2">7.22.1</A>)</TD>
<TD VALIGN=top ALIGN=center NOWRAP> </TD>
<TD VALIGN=top ALIGN=left><TT>representation_error(max_arity)</TT></TD>
</TR>
<TR><TD BGCOLOR=black COLSPAN=3><TABLE BORDER=0 WIDTH="100%" CELLSPACING=0 CELLPADDING=1><TR><TD></TD></TR></TABLE></TD>
</TR>
<TR><TD VALIGN=top ALIGN=left><TT>Property</TT> is neither a variable nor a predicate property
term</TD>
<TD VALIGN=top ALIGN=center NOWRAP> </TD>
<TD VALIGN=top ALIGN=left><TT>domain_error(predicate_property, Property)</TT></TD>
</TR>
<TR><TD BGCOLOR=black COLSPAN=3><TABLE BORDER=0 WIDTH="100%" CELLSPACING=0 CELLPADDING=1><TR><TD></TD></TR></TABLE></TD>
</TR>
<TR><TD VALIGN=top ALIGN=left><TT>Property</TT> = <TT>prolog_file(File)</TT> and <TT>File</TT>
is neither a variable nor an atom</TD>
<TD VALIGN=top ALIGN=center NOWRAP> </TD>
<TD VALIGN=top ALIGN=left><TT>type_error(atom, File)</TT></TD>
</TR>
<TR><TD BGCOLOR=black COLSPAN=3><TABLE BORDER=0 WIDTH="100%" CELLSPACING=0 CELLPADDING=1><TR><TD></TD></TR></TABLE></TD>
</TR>
<TR><TD VALIGN=top ALIGN=left><TT>Property</TT> = <TT>prolog_line(Line)</TT> and <TT>Line</TT>
is neither a variable nor an integer</TD>
<TD VALIGN=top ALIGN=center NOWRAP> </TD>
<TD VALIGN=top ALIGN=left><TT>type_error(integer, Line)</TT></TD>
</TR>
<TR><TD BGCOLOR=black COLSPAN=3><TABLE BORDER=0 WIDTH="100%" CELLSPACING=0 CELLPADDING=1><TR><TD></TD></TR></TABLE></TD>
</TR></TABLE><BR>
<B>Portability</B><BR>
<BR>
GNU Prolog predicate.<BR>
<BR>
<HR SIZE=2>
Copyright (C) 1999-2007 Daniel Diaz
<BR>
<BR>
Verbatim copying and distribution of this entire article is permitted in any
medium, provided this notice is preserved. <BR>
<BR>
<A HREF="index.html#copyright">More about the copyright</A>
<HR>
<A HREF="gprolog030.html"><IMG SRC ="previous_motif.gif" ALT="Previous"></A>
<A HREF="gprolog023.html"><IMG SRC ="contents_motif.gif" ALT="Up"></A>
<A HREF="gprolog032.html"><IMG SRC ="next_motif.gif" ALT="Next"></A>
</BODY>
</HTML>
|
