Merge pull request cantools#265 from altendky/patch-1

lack of matplolib does not error until actually running subcommand
Gussy · Feb 9, 2021 · d396fbd · d396fbd
2 parents a5029b5 + f35ba93
commit d396fbd
Showing 1 changed file with 17 additions and 4 deletions.
diff --git a/cantools/subparsers/plot.py b/cantools/subparsers/plot.py
@@ -51,14 +51,23 @@
 try:
     from matplotlib import pyplot as plt
 except ImportError:
-    print("matplotlib package not installed. Required for producing plots.")
+    plt = None
 
 from .. import database
+from .. import errors
 
 
-plt.rcParams["date.autoformatter.hour"] = "%H:%M"
-plt.rcParams["date.autoformatter.minute"] = "%H:%M"
-plt.rcParams["date.autoformatter.microsecond"] = "%H:%M:%S.%f"
+class MatplotlibNotInstalledError(errors.Error):
+
+    def __init__(self):
+        super().__init__("The matplotlib package not installed and is required "
+                         "for producing plots.")
+
+
+if plt is not None:
+    plt.rcParams["date.autoformatter.hour"] = "%H:%M"
+    plt.rcParams["date.autoformatter.minute"] = "%H:%M"
+    plt.rcParams["date.autoformatter.microsecond"] = "%H:%M:%S.%f"
 
 
 # Matches 'candump' output, i.e. "vcan0  1F0   [8]  00 00 00 00 00 00 1B C1".
@@ -178,6 +187,10 @@ def _do_decode(args):
     It iterates over all input lines, parses them
     and passes the data to a Plotter object.
     '''
+
+    if plt is None:
+        raise MatplotlibNotInstalledError()
+
     if args.show_errors:
         args.show_invalid_syntax = True
         args.show_unknown_frames = True