[LyX/master] Remove alternative operator representations (and, or) and improve comments for python binary detection.

[José Matos]

commit 35c299f86d35385b5bf3729682eeb8d2eb1c78a4
Author: José Matos <jama...@lyx.org>
Date:   Sat Jun 8 09:15:03 2019 +0100

    Remove alternative operator representations (and,or) and improve comments 
for python binary detection.
---
 src/support/os.cpp |   26 ++++++++++++++++----------
 1 files changed, 16 insertions(+), 10 deletions(-)

diff --git a/src/support/os.cpp b/src/support/os.cpp
index 936e759..d435575 100644
--- a/src/support/os.cpp
+++ b/src/support/os.cpp
@@ -56,7 +56,7 @@ static string const python23(string const & binary, bool 
verbose = false)
 
        int major = convert<int>(sm.str(1));
        int minor = convert<int>(sm.str(2));
-       if((major == 2 and minor < 7) or (major == 3 and minor < 4))
+       if((major == 2 && minor < 7) || (major == 3 && minor < 4))
                return string();
 
        if (verbose)
@@ -73,6 +73,12 @@ int timeout_min()
 
 string const python(bool reset)
 {
+       // This function takes inspiration from PEP 394 and PEP 397
+       // PEP 394 -- The "python" Command on Unix-Like Systems
+       // https://www.python.org/dev/peps/pep-0394/
+       // PEP 397 -- Python launcher for Windows
+       // https://www.python.org/dev/peps/pep-0397/
+
        // Check whether python3 in PATH is the right one.
        static string command = python23("python3");
        // FIXME THREAD
@@ -80,10 +86,10 @@ string const python(bool reset)
                command = python23("python3");
        }
 
-       // python3 does not exists, let us try python3.x
+       // python3 does not exists, let us try to find python3.x in PATH
+       // the search is probably broader than required
+       // but we are trying hard to find a valid python binary
        if (command.empty()) {
-               // It was not, so check whether we can find it elsewhere in
-               // PATH, maybe with some suffix appended.
                vector<string> const path = getEnvPath("PATH");
                lyxerr << "Looking for python 3.x ...\n";
                for (auto bin: path) {
@@ -100,16 +106,16 @@ string const python(bool reset)
                }
 
        }
-       // python 3 not found let us look for python 2
+       // python 3 was not found let us look for python 2
        if (command.empty())
                command = python23("python2");
 
-       // python2 does not exists, let us try python2.x
+       // python2 does not exists, let us try to find python2.x in PATH
+       // the search is probably broader than required
+       // but we are trying hard to find a valid python binary
        if (command.empty()) {
-               // It was not, so check whether we can find it elsewhere in
-               // PATH, maybe with some suffix appended.
                vector<string> const path = getEnvPath("PATH");
-               lyxerr << "Looking for python 3.x ...\n";
+               lyxerr << "Looking for python 2.x ...\n";
                for (auto bin: path) {
                        QString const dir = toqstr(bin);
                        string const localdir = dir.toLocal8Bit().constData();
@@ -126,7 +132,7 @@ string const python(bool reset)
        }
 
        // Default to "python" if no usable binary was found.
-       // If this happens all hope is lost that there is a sane system
+       // If this happens all hope is lost that this is a sane system
        if (command.empty()) {
                lyxerr << "Warning: No python v2.x or 3.x binary found.\n";
                command = "python";