improved dependency checking

coub-dl.py

@@ -16,6 +16,7 @@ from functools import wraps
 from tempfile import mkdtemp
 from shutil import rmtree
 from signal import signal, SIGINT
+from sys import exit
 
 
 
@@ -145,30 +146,17 @@ def mux_streams(file_dict):
          stdout=DEVNULL, stderr=DEVNULL)
 
 
-@call_verbose(before_message='Checking your system for youtube-dl and ffmpeg... ', after_message='Found both!')
-def check_for_ytdl_and_ffmpeg():
-    error_str = '\nNo {} found in PATH! coub-dl requires youtube-dl & ffmpeg.'
-    ytdl_found = False
-    ffmpeg_found = False
-    try:
-        check_output(('youtube-dl', '--version'))
-        ytdl_found = True
-    except (CalledProcessError, FileNotFoundError):
-        pass
-    try:
-        check_output(('ffmpeg', '-version'))
-        ffmpeg_found = True
-    except (CalledProcessError, FileNotFoundError):
-        pass
+@call_verbose(before_message='Checking your system for dependencies... ', after_message='Found all!')
+def check_for_dependencies():
+    check_for = (('youtube-dl', '--version'), ('ffmpeg', '-version'), ('curl', '--version'))
+    error_str = '\nMissing dependencies: {}'
+    missing = []
 
-    if not ytdl_found and not ffmpeg_found:
-        print_opt(error_str.format('youtube-dl nor ffmpeg'))
-    elif not ytdl_found:
-        print_opt(error_str.format('youtube-dl'))
-    elif not ffmpeg_found:
-        print_opt(error_str.format('ffmpeg'))
+    for command in check_for:
+        try: check_output(command)
+        except (CalledProcessError, FileNotFoundError): missing.append(command[0])
 
-    if not ytdl_found or not ffmpeg_found: exit()
+    if missing: exit(error_str.format(', '.join(missing)))
 
 
 def determine_output_filename(url, user_supplied, extension, files_dict):
@@ -243,7 +231,7 @@ if __name__ == '__main__':
     args = parse_cmd_arguments()
     VERBOSE = False if args.nonverbose else True
 
-    check_for_ytdl_and_ffmpeg()
+    check_for_dependencies()
 
     # create dict that contains files used
     FILES, OUTPUT_KEYS = build_default_files_dict()