Use constexpr to avoid a static initializer

webrtc/modules/audio_processing/vad/vad_audio_proc.cc

 /*
  *  Copyright (c) 2012 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 15 matching lines @@
 }
 #include "webrtc/modules/include/module_common_types.h"
 
 namespace webrtc {
 
 // The following structures are declared anonymous in iSAC's structs.h. To
 // forward declare them, we use this derived class trick.
 struct VadAudioProc::PitchAnalysisStruct : public ::PitchAnalysisStruct {};
 struct VadAudioProc::PreFiltBankstr : public ::PreFiltBankstr {};
 
-static const float kFrequencyResolution =
+constexpr float kFrequencyResolution =

[kwiberg-webrtc, 2017/06/17 22:54:30]

That constexpr (and const) imply internal linkage is probably not well enough
known---consider e.g. that this declaration and that on the next line were both
"static const". Could you put it in an unnamed namespace to make the internal
linkage obvious?

(Also, to reduce eyesore, give the kSilenceRms declaration the same treatment if
you want.)

[hlundin-webrtc, 2017/06/19 07:45:23]

What kwiberg@ says.

[brucedawson, 2017/06/19 18:45:56]

I added constexpr to kSilenceRms, to make it appear more consistent.

I agree that removing static may cause some confusion so I put it back. I can't
convince myself to put the declarations in an anonymous namespace that I know is
unnecessary so I think restoring static is the right compromise.

     kSampleRateHz / static_cast<float>(VadAudioProc::kDftSize);
 static const int kSilenceRms = 5;
 
 // TODO(turajs): Make a Create or Init for VadAudioProc.
 VadAudioProc::VadAudioProc()
     : audio_buffer_(),
       num_buffer_samples_(kNumPastSignalSamples),
       log_old_gain_(-2),
       old_lag_(50),  // Arbitrary but valid as pitch-lag (in samples).
       pitch_analysis_handle_(new PitchAnalysisStruct),
@@ skipping 220 matching lines @@
   size_t offset = kNumPastSignalSamples;
   for (size_t i = 0; i < kNum10msSubframes; i++) {
     rms[i] = 0;
     for (size_t n = 0; n < kNumSubframeSamples; n++, offset++)
       rms[i] += audio_buffer_[offset] * audio_buffer_[offset];
     rms[i] = sqrt(rms[i] / kNumSubframeSamples);
   }
 }
 
 }  // namespace webrtc