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The correct way to implement -Whatif and -Confirm in a Powershell Cmdlet

January 08, 2019 — Jesse Harris

When I first learned about [CmdLetBinding()] to add automatic support for Write-Verbose I didn't understand why -WhatIf and -Confirm were not passed to Cmdlets used in my functions.


How I Code

May 24, 2018 — Jesse Harris

Updated 17/08/2018

Coding can be fun. I've enjoyed coding from a young age, starting with GW-Basic at maybe 6, 7, or 8.

I remember my brother Alex seemed like a real genius with the computer (an IBM clone made by Acer 8086 XT). Using Basic he could make the computer do anything and was writing his own games.

Back then, how we edited code would make us laugh today and I would say we take the humble text editor for granted. Even something like notepad.exe is amazing compared to tools of yesteryear. Here is a sample to illustrate: To see your code you would have to type LIST<ENTER>:


    30 $I = INPUT

To edit a line of code you would re-write it by typing it in, line number and all.


And to insert a line, start a line with a number between existing lines

    31 $A=$I

When you ran out of in-between-lines there was a command you could run to reindex your lines which would space them all out 10 between each other.

Since then, the notepad, notepad++, programmers notepad, vim, nano, gedit, bbedit and countless other advanced (or not-so-advanced) text editors have evolved.

vi was born out of ed a streaming text editor which didn't really have a user interface so it was kind of more like how I edited my BASIC programs. One thing it did have were commands. Example of vim commands:

You've just run your script/app and get a syntax error on line 432.

 PS> .\bigscript.ps1
 At C:\bigscript.ps1:432 char:27
 + if ($true) {echo "True" | {echo true}}
 +                           ~~~~~~~~~~~
 Expressions are only allowed as the first element of a pipeline.
 + CategoryInfo          : ParserError: (:) [], ParseException
 + FullyQualifiedErrorId : ExpressionsMustBeFirstInPipeline

So you crack open bigscript in vim (btw, vim is amazing at handling big files) Enter, 432Gf|a?<ESC>:wq done.

To break that down, 432G will put the cursor at line 432, f| will move the cursor forward to the |, a? will append a ?, then \ will return vim back to normal mode and :wq puts vim in command mode and execute write quit.

Now that might seem a bit obtuse if your not a vim user, but to me that is muscle memory and if coding is your life, this is something you are going to want to learn.

If this interests you, and you start your vim journey, then read on. I will share my vim configuration and history of using vim.

My vim story

When my Dad was about the same age as I am now (35), he went back to University to study Computer Science. I remember him bringing home Slackware and RedHat on floppies, which we would install and he would give me lessons on using Vi possibly vim, but I didn't know at the time. (This is probably around 1996).

Since finishing School and entering the workforce I have mostly worked in Windows environments. Even still, with the occasionaly need to touch GNU/Linux at work and often testing Distro's at home I would always feel more efficient when using Vi/m.

My feeling when using another editor is that moving around and changing text feels so lethargic when done one button at a time. This drove me in recent years to keep a copy of vim in my home profile.

Around 2011 I switched from VBScript and the occasional perl script to writing fulltime in Powershell, so it made sense to try a few different editors which are more native to the Windows platform. I tried Visual Studio Code, Powershell ISE, Notepad++ and still kept coming back to vim.

Visual Studio Code is a great alternative, and it's Powershell extensions are very good. If you do choose to use it, install the vim extension too. It brings the vim commands to vscode. Hoever being an electron app, it suffers from performance and memory consumption issues. I love squeezing every drop of battery out of my PC and when you see 7mb RAM on Vim vs 500Mb+ on VSCode, you might rethink your choices.

Therefore I've resorted to delving into the world of customizing vim and setting up plugins.

One of the main things I'm trying to acheive is a cross platform configuration. You see, at work I'm on Windows and MacOs and at home I'm on Gentoo Linux. So I have written my .vimrc file to work on any platform. I usually sync it with OneDrive for Business and symlink it into my linux/mac/Windows home directory with a seperate setup script. Without further ado, here it is with some comments


if has("win32")                               " Check if on windows \
                                              " Also supports has(unix)
    source $VIMRUNTIME/mswin.vim              " Load a special vimscript \
                                              " ctrl+c and ctrl+v support
    behave mswin                              " Like above
    set ff=dos                                " Set file format to dos
    let os='win'                              " Set os var to win
    set noeol                                 " Don't add an extra line \
                                              " at the end of each file
    set nofixeol                              " Disable the fixeol : Not \
                                              " not sure why this is needed
    set backupdir=~/_vimtmp,.                 " Set backupdir rather \
                                              " than leaving backup files \
                                              " all over the fs
    set directory=~/_vimtmp,.                 " Set dir for swp files \
                                              " rather than leaving files \
                                              " all over the fs
    set undodir=$USERPROFILE/vimfiles/VIM_UNDO_FILES " Set persistent undo\
                                              " files
                                              " directory
    let plug='$USERPROFILE/.vim'              " Setup a var used later to \
                                              " store plugins
    set shell=powershell                      " Set shell to powershell \
                                              " on windows
    set shellcmdflag=-command                 " Arg for powrshell to run
    set backupdir=~/.vimtmp,.
    set directory=~/.vimtmp,.
    set undodir=$HOME/.vim/VIM_UNDO_FILES
    let uname = system('uname')               " Check variant of Unix \
                                              " running. Linux|Macos
    if uname =~ "Darwin"                      " If MacOS
        let plug='~/.vim'
        let os='mac'                          " Set os var to mac
        if isdirectory('/mnt/c/Users/jpharris')
            let plug='/mnt/c/Users/jpharris/.vim'
            let os='wsl'
            let plug='~/.vim'
            let os='lin'

execute "source " . plug . "/autoload/plug.vim"
if exists('*plug#begin')
    call plug#begin(plug . '/plugged')       " Enable the following plugins
    Plug 'tpope/vim-fugitive'
    Plug 'junegunn/gv.vim'
    Plug 'junegunn/vim-easy-align'
    Plug 'jiangmiao/auto-pairs'
    "Plug 'vim-airline/vim-airline'          " Airline disabled for perf
    Plug 'morhetz/gruvbox'
    Plug 'ervandew/supertab'
    Plug 'tomtom/tlib_vim'
    Plug 'MarcWeber/vim-addon-mw-utils'
    Plug 'PProvost/vim-ps1'
    Plug 'garbas/vim-snipmate'
    Plug 'honza/vim-snippets'
    call plug#end()
                                             " Remove menu bars
if has("gui_running")                        " Options for gvim only
    set guioptions -=m                       " Disable menubar
    set guioptions -=T                       " Disable Status bar
    set lines=50                             " Set default of lines
    set columns=80                          " Set default of columns
    if os =~ "lin"
        set guifont=Fira\ Code\ 12
    elseif os =~ "mac"
        set guifont=FiraCode-Retina:h14
        set guifont=Fira_Code_Retina:h12:cANSI:qDRAFT
        set renderoptions=type:directx
        set encoding=utf-8
    set background=dark
    colorscheme gruvbox
    set mouse=a
    if has('termguicolors')
        set termguicolors                    " Enable termguicolors for \
                                             " consoles which support 256.
        set background=dark
        colorscheme gruvbox

if has("persistent_undo")
    set undofile                             " Enable persistent undo

colorscheme evening                          " Set the default colorscheme
                                             " Attempt to start vim-plug

syntax on                                    " Enable syntax highlighting
filetype plugin indent on                    " Enable plugin based auto \
                                             " indent
set tabstop=4                                " show existing tab with 4 \
                                             " spaces width
set shiftwidth=4                             " when indenting with '>', \
                                             " use 4 spaces width
set expandtab                                " On pressing tab, insert 4 \
                                             " spaces
set number                                   " Show line numbers

" Map F5 to python.exe %=current file
nnoremap <silent> <F5> :!clear;python %<CR>
" Remap tab to auto complete 
imap <C-@> <C-Space>
" Setup ga shortcut for easyaline in visual mode
nmap ga <Plug>(EasyAlign)
" Setup ga shortcut for easyaline in normal mode
xmap ga <Plug>(EasyAlign)"

Link to vimrc on github

Tags: vim, coding, windows, linux, macos