Improved exporting procedure

* improved code readability

prasopes/filetools.py

@@ -8,7 +8,7 @@ def open_dial(d_set):
     filename = QtWidgets.QFileDialog.getOpenFileName(
             caption="Open spectrum",
             filter="Finnigan RAW files (*.raw, *.RAW)")[0]
-    if filename is not'':
+    if filename is not '':
         d_set['chrom_dat'], d_set['masses'], d_set['matrix'] \
              = load_raw(filename)
         return filename
@@ -16,6 +16,28 @@ def open_dial(d_set):
         return None
 
 
+def get_save_filename(caption, fnfilter, suffix, parent):
+    """fix Qt5 "feature" - it does add sufix when exporting
+    and thus also cant check for file with the selected suffix"""
+    filename = QtWidgets.QFileDialog.getSaveFileName(
+            caption=caption, filter=fnfilter,
+            options = QtWidgets.QFileDialog.DontConfirmOverwrite)[0]
+    if suffix[0] is not ".":
+        suffix = ".{}".format(suffix)
+    if filename[-len(suffix):] != suffix:
+        filename = "".join((filename, suffix))
+    if os.path.isfile(filename):
+        quest = QtWidgets.QMessageBox.warning(
+           parent, caption,
+           "File {} already exists in the filesystem.\n"
+           "Do you want to overwrite it?"
+           .format(os.path.basename(filename)),
+           QtWidgets.QMessageBox.Yes, QtWidgets.QMessageBox.No)
+        if quest == QtWidgets.QMessageBox.No:
+            filename = ''
+    return filename
+
+
 def export_dial(mass_spec, chrom_spec, fn, main_window):
     """exports the chromatogram into the .dat file format"""
     if fn[0] is None:
@@ -23,21 +45,9 @@ def export_dial(mass_spec, chrom_spec, fn, main_window):
             main_window, "Export spectrum",
             "Nothing to export, cancelling request")
         return
-    exp_f_name = QtWidgets.QFileDialog.getSaveFileName(
-            caption="Export spectrum",
-            filter="dat table format (*.dat)")[0]
+    exp_f_name = get_save_filename(
+        "Export spectrum", "dat table (*.dat)", "dat", main_window)
     if exp_f_name is not '':
-        # fix for Qt5 "Feature"
-        if exp_f_name[-4:] != '.dat':
-            exp_f_name = exp_f_name + ".dat"
-            if os.path.isfile(exp_f_name):
-                quest = QtWidgets.QMessageBox.warning(
-                    main_window, "Export spectrum",
-                    "{} already exists.\n Do you want to replace it?"
-                    .format(os.path.basename(exp_f_name)),
-                    QtWidgets.QMessageBox.Yes, QtWidgets.QMessageBox.No)
-                if(hex(quest)) == "0x10000":
-                    return
         expf = open(exp_f_name, 'w')
         expf.write("mass ion_count\n" 
                    "m/z\n" 

prasopes/zcetools.py

-import numpy as np
-import prasopes.graphtools as gt
-import os.path
-import pkg_resources
 from matplotlib.backends.backend_qt5agg import FigureCanvasQTAgg as FigureCanvas
 from matplotlib.figure import Figure
 from PyQt5 import QtCore
 from PyQt5 import QtWidgets
+import numpy as np
+import prasopes.graphtools as gt
+import prasopes.filetools as ft
+import os.path
+import pkg_resources
 
 
 def pop_dial(zcespec, gradspect, data_set, widget, coff_d, grad_d,
@@ -61,21 +62,9 @@ def exp_zce(zce_spec, zcegrad_spec, fn, parent):
             parent, "Export ZCE spectrum",
             "Nothing to export, cancelling request")
         return
-    exp_f_name = QtWidgets.QFileDialog.getSaveFileName(
-            caption="Export ZCE spectrum",
-            filter="dat table format (*.dat)")[0]
+    exp_f_name = ft.get_save_filename(
+        "Export ZCE spectrum", "dat table (*.dat)", "dat", parent)
     if exp_f_name is not '':
-        # fix for Qt5 "Feature"
-        if exp_f_name[-4:] != '.dat':
-            exp_f_name = exp_f_name + ".dat"
-            if os.path.isfile(exp_f_name):
-                quest = QtWidgets.QMessageBox.warning(
-                    parent, "Export spectrum",
-                    "{} already exists.\n Do you want to replace it?"
-                    .format(os.path.basename(exp_f_name)),
-                    QtWidgets.QMessageBox.Yes, QtWidgets.QMessageBox.No)
-                if(hex(quest)) == "0x10000":
-                    return
         expf = open(exp_f_name, 'w')
         expf.write("mass ion_count ion_count_gradient fwhm_x fwhm_y\n"
                    "m/z\n"