1 // Copyright (c) 2008, Google Inc.
2 // All rights reserved.
4 // Redistribution and use in source and binary forms, with or without
5 // modification, are permitted provided that the following conditions are
8 // * Redistributions of source code must retain the above copyright
9 // notice, this list of conditions and the following disclaimer.
10 // * Redistributions in binary form must reproduce the above
11 // copyright notice, this list of conditions and the following disclaimer
12 // in the documentation and/or other materials provided with the
14 // * Neither the name of Google Inc. nor the names of its
15 // contributors may be used to endorse or promote products derived from
16 // this software without specific prior written permission.
18 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
19 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
20 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
21 // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
22 // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
23 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
24 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
25 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
26 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
27 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
28 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
31 // This file is a compatibility layer that defines Google's version of
32 // command line flags that are used for configuration.
34 // We put flags into their own namespace. It is purposefully
35 // named in an opaque way that people should have trouble typing
36 // directly. The idea is that DEFINE puts the flag in the weird
37 // namespace, and DECLARE imports the flag from there into the
38 // current namespace. The net result is to force people to use
39 // DECLARE to get access to a flag, rather than saying
40 // extern bool FLAGS_logtostderr;
41 // or some such instead. We want this so we can put extra
42 // functionality (like sanity-checking) in DECLARE if we want,
43 // and make sure it is picked up everywhere.
45 // We also put the type of the variable in the namespace, so that
46 // people can't DECLARE_int32 something that they DEFINE_bool'd
48 #ifndef BASE_COMMANDLINEFLAGS_H__
49 #define BASE_COMMANDLINEFLAGS_H__
53 #include <string.h> // for memchr
54 #include <stdlib.h> // for getenv
56 #ifdef HAVE_LIB_GFLAGS
58 #include <gflags/gflags.h>
62 #include "glog/logging.h"
64 #define DECLARE_VARIABLE(type, shorttype, name, tn) \
65 namespace fL##shorttype { \
66 extern GOOGLE_GLOG_DLL_DECL type FLAGS_##name; \
68 using fL##shorttype::FLAGS_##name
69 #define DEFINE_VARIABLE(type, shorttype, name, value, meaning, tn) \
70 namespace fL##shorttype { \
71 GOOGLE_GLOG_DLL_DECL type FLAGS_##name(value); \
72 char FLAGS_no##name; \
74 using fL##shorttype::FLAGS_##name
76 // bool specialization
77 #define DECLARE_bool(name) \
78 DECLARE_VARIABLE(bool, B, name, bool)
79 #define DEFINE_bool(name, value, meaning) \
80 DEFINE_VARIABLE(bool, B, name, value, meaning, bool)
82 // int32 specialization
83 #define DECLARE_int32(name) \
84 DECLARE_VARIABLE(GOOGLE_NAMESPACE::int32, I, name, int32)
85 #define DEFINE_int32(name, value, meaning) \
86 DEFINE_VARIABLE(GOOGLE_NAMESPACE::int32, I, name, value, meaning, int32)
88 // Special case for string, because we have to specify the namespace
89 // std::string, which doesn't play nicely with our FLAG__namespace hackery.
90 #define DECLARE_string(name) \
92 extern GOOGLE_GLOG_DLL_DECL std::string& FLAGS_##name; \
94 using fLS::FLAGS_##name
95 #define DEFINE_string(name, value, meaning) \
97 std::string FLAGS_##name##_buf(value); \
98 GOOGLE_GLOG_DLL_DECL std::string& FLAGS_##name = FLAGS_##name##_buf; \
99 char FLAGS_no##name; \
101 using fLS::FLAGS_##name
103 #endif // HAVE_LIB_GFLAGS
105 // Define GLOG_DEFINE_* using DEFINE_* . By using these macros, we
106 // have GLOG_* environ variables even if we have gflags installed.
108 // If both an environment variable and a flag are specified, the value
109 // specified by a flag wins. E.g., if GLOG_v=0 and --v=1, the
110 // verbosity will be 1, not 0.
112 #define GLOG_DEFINE_bool(name, value, meaning) \
113 DEFINE_bool(name, EnvToBool("GLOG_" #name, value), meaning)
115 #define GLOG_DEFINE_int32(name, value, meaning) \
116 DEFINE_int32(name, EnvToInt("GLOG_" #name, value), meaning)
118 #define GLOG_DEFINE_string(name, value, meaning) \
119 DEFINE_string(name, EnvToString("GLOG_" #name, value), meaning)
121 // These macros (could be functions, but I don't want to bother with a .cc
122 // file), make it easier to initialize flags from the environment.
124 #define EnvToString(envname, dflt) \
125 (!getenv(envname) ? (dflt) : getenv(envname))
127 #define EnvToBool(envname, dflt) \
128 (!getenv(envname) ? (dflt) : memchr("tTyY1\0", getenv(envname)[0], 6) != NULL)
130 #define EnvToInt(envname, dflt) \
131 (!getenv(envname) ? (dflt) : strtol(getenv(envname), NULL, 10))
133 #endif // BASE_COMMANDLINEFLAGS_H__