(self, use_user_site)
return True
Find an installed distribution that satisfies or conflicts
        with this requirement, and set self.satisfied_by or
        self.conflicts_with appropriately.
Find an installed distribution that satisfies or conflicts
        with this requirement, and set self.satisfied_by or
        self.conflicts_with appropriately.
Find an installed distribution that satisfies or conflicts with this requirement and set self . satisfied_by or self . conflicts_with appropriately .
def check_if_exists(self, use_user_site):
        # type: (bool) -> bool
        """Find an installed distribution that satisfies or conflicts
        with this requirement, and set self.satisfied_by or
        self.conflicts_with appropriately.
        """
        if self.req is None:
            return False
        try:
            # get_distribution() will resolve the entire list of requirements
            # anyway, and we've already determined that we need the requirement
            # in question, so strip the marker so that we don't try to
            # evaluate it.
            no_marker = Requirement(str(self.req))
            no_marker.marker = None
            self.satisfied_by = pkg_resources.get_distribution(str(no_marker))
            if self.editable and self.satisfied_by:
                self.conflicts_with = self.satisfied_by
                # when installing editables, nothing pre-existing should ever
                # satisfy
                self.satisfied_by = None
                return True
        except pkg_resources.DistributionNotFound:
            return False
        except pkg_resources.VersionConflict:
            existing_dist = pkg_resources.get_distribution(
                self.req.name
            )
            if use_user_site:
                if dist_in_usersite(existing_dist):
                    self.conflicts_with = existing_dist
                elif (running_under_virtualenv() and
                        dist_in_site_packages(existing_dist)):
                    raise InstallationError(
                        "Will not install to the user site because it will "
                        "lack sys.path precedence to %s in %s" %
                        (existing_dist.project_name, existing_dist.location)
                    )
            else:
                self.conflicts_with = existing_dist
        return True
def check_if_exists ( self , use_user_site ) : # type: (bool) -> bool if self . req is None : return False try : # get_distribution() will resolve the entire list of requirements # anyway, and we've already determined that we need the requirement # in question, so strip the marker so that we don't try to # evaluate it. no_marker = Requirement ( str ( self . req ) ) no_marker . marker = None self . satisfied_by = pkg_resources . get_distribution ( str ( no_marker ) ) if self . editable and self . satisfied_by : self . conflicts_with = self . satisfied_by # when installing editables, nothing pre-existing should ever # satisfy self . satisfied_by = None return True except pkg_resources . DistributionNotFound : return False except pkg_resources . VersionConflict : existing_dist = pkg_resources . get_distribution ( self . req . name ) if use_user_site : if dist_in_usersite ( existing_dist ) : self . conflicts_with = existing_dist elif ( running_under_virtualenv ( ) and dist_in_site_packages ( existing_dist ) ) : raise InstallationError ( "Will not install to the user site because it will " "lack sys.path precedence to %s in %s" % ( existing_dist . project_name , existing_dist . location ) ) else : self . conflicts_with = existing_dist return True