Changes between Version 22 and Version 23 of CodeBestPractices
- Timestamp:
- 2012-12-01 11:18:56 (11 years ago)
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CodeBestPractices
v22 v23 1 1 = Best practices when coding EwE6 = 2 2 This page describes standard solutions for recurring oddities and nasties that we have ran into over the years when building EwE6. 3 4 '' THIS SECTION IS UNDER DEVELOPMENT '' 3 5 4 6 The following issues are discussed on this page: … … 17 19 18 20 ---- 21 19 22 == Robustness == 20 23 … … 23 26 === Try / Catch === 24 27 25 Make your code robust to failures by encapsulating big function calls in [http://www.homeandlearn.co.uk/net/nets5p4.html Try / Catch] blocks. Public methods on public classes are often the entry point to deeper functionality, and placing a Try / Catch inside the public methods is a good way to capture any internal failures within your code. We've done the same in the plug-in framework, where every plug-in point call is wrapped in a Try / Catch block to make sure EwE is not affected by a failing plug-in point or button click.28 Make your code robust to failures by encapsulating big function calls in [http://www.homeandlearn.co.uk/net/nets5p4.html Try / Catch] blocks. Public methods in public classes are often the entry point to deeper functionality, and placing a Try / Catch inside the public methods is a good way to capture any internal failures within your code. We've done the same in the plug-in framework, where every plug-in point call is wrapped in a Try / Catch block to make sure EwE is not affected by a failing plug-in point or button click. 26 29 27 30 Take for instance the code that runs in response to a 'Run' button click on the Run Ecosim form: 28 31 {{{ 29 30 32 Private Sub OnRun(ByVal sender As System.Object, ByVal e As System.EventArgs) _ 33 Handles m_btnRun.Click 31 34 32 '''Try'''33 34 35 36 37 38 '''Catch ex As Exception'''39 40 '''End Try'''35 Try 36 If Not Me.IsRunning Then 37 Me.m_iTimeSteps = Me.Core.nEcosimTimeSteps 38 Me.m_graph.Refresh() 39 Me.Core.RunEcoSim(AddressOf TimeStepFromEcoSim_handler, True) 40 End If 41 Catch ex As Exception 42 cLog.Write(ex, "form RunEcosim.OnRun") 43 End Try 41 44 42 45 End Sub 43 46 }}} 44 47 … … 49 52 The EwE Log file, created and managed by the core, and stored in the Windows application data folder, contains a track list of important actions taken by EwE in response to user requests and a track record of failures and successes. The purpose of the log is to provide postmortem diagnostics when an error has occurred. You can use the log as well in your plug-ins. Frankly, we think you should. 50 53 51 If you strategically encapsulate [#try_/_cath Try / Catch] blocks, why not write the result of the exception to the log file: 54 If you strategically encapsulate [#try_/_cath Try / Catch] blocks, why not write the result of the exception to the log file, as shown here in the Catch part of the try/catch block: 55 {{{ 56 Private Sub OnRun(ByVal sender As System.Object, ByVal e As System.EventArgs) _ 57 Handles m_btnRun.Click 52 58 53 Take for instance the code that runs in response to a 'Run' button click on the Run Ecosim form: 59 Try 60 If Not Me.IsRunning Then 61 Me.m_iTimeSteps = Me.Core.nEcosimTimeSteps 62 Me.m_graph.Refresh() 63 Me.Core.RunEcoSim(AddressOf TimeStepFromEcoSim_handler, True) 64 End If 65 Catch ex As Exception 66 cLog.Write(ex, "form RunEcosim.OnRun") 67 End Try 68 69 End Sub 70 }}} 71 72 === Assertions === 73 74 Make it a habit to make your code as sound as it can get by testing whether [http://www.homeandlearn.co.uk/net/nets5p1.html your code is properly used]. [http://msdn.microsoft.com/en-us/library/system.diagnostics.debug.assert%28v=vs.71%29.aspx Assertions] are a neat way to slap yourself on the wrist if built-in assumptions in your code are somehow failing. In EwE, we sometimes refer to these checks as ''sanity checks'' ;-) In released versions of EwE assertions will not show up, but they are a good tool to check whether your code is used as it is supposed to while developing. 75 76 To illustrate, does the following code make sense? 54 77 {{{ 55 Private Sub OnRun(ByVal sender As System.Object, ByVal e As System.EventArgs) _ 56 Handles m_btnRun.Click 78 Public Function Div(ByVal dividend As Single, ByVal divider As Single) As Single 57 79 58 Try 59 If Not Me.IsRunning Then 60 Me.m_iTimeSteps = Me.Core.nEcosimTimeSteps 61 Me.m_graph.Refresh() 62 Me.Core.RunEcoSim(AddressOf TimeStepFromEcoSim_handler, True) 63 End If 64 Catch ex As Exception 65 '''cLog.Write(ex, "form RunEcosim.OnRun")''' 66 End Try 80 'Sanity checks 81 Debug.Assert(dividend <> 0, "Cannot divide by zero") 67 82 68 End Sub 83 Return dividend / divider 84 85 End Function 69 86 }}} 87 70 88 ---- 71 89
