The Wiert Corner – irregular stream of stuff

Jeroen W. Pluimers on .NET, C#, Delphi, databases, and personal interests

  • My badges

  • Twitter Updates

  • Pages

  • All categories

  • Enter your email address to subscribe to this blog and receive notifications of new posts by email.

    Join 1,854 other subscribers

Archive for the ‘Software Development’ Category

Automated clicking on HTML elements – Chee Wee’s blog

Posted by jpluimers on 2019/12/03

Magic from the JavaScript console: [WayBackAutomated clicking on HTML elements – Chee Wee’s blog: IT solutions for Singapore and companies worldwide.

This is the code he uses because [WayBackgetElementsByClassName returns an array ([WayBack] getElementById returns one reference or null, but many sites still develop without assigning an ID to their elements):

function clickRefresh() {
  ImStillHere = document.getElementsByClassName("Button Success");
  if (ImStillHere.length > 0)
    ImStillHere[0].click();
  document.getElementsByClassName("refresh-widget")[0].click();
}
setInterval(clickRefresh, 1000);

via: [WayBack] function clickRefresh(){ … – CHUA Chee Wee – Google+

I like the approach. Now I need to find a way to automate this in some kind of plug-in.

–jeroen

Posted in Development, JavaScript/ECMAScript, Scripting, Software Development | Leave a Comment »

bash: converting numbers to human readable SI or IEC units

Posted by jpluimers on 2019/12/03

Many unix tools that report sizes in bytes can convert them to either IEC or SI readable formats.

For github.com/jpluimers/btrfs-du/blob/master/btrfs-du I wrote about last week, I also wanted that kind of behaviour. So I did some research and came up with the code and test cases below.

Note that depending on the bitness of your system, bash integer numeric values are limited in size; see [WayBack] What is the maximum value of a numeric bash shell variable? – Super User.

So I wrote a small bash script for that too, which needed also gave me the opportunity to show how a  perpetual while loop as explained by [WayBack] bash – “while :” vs. “while true” – Stack Overflow.

Two things that always bite me with these short scripts are expressions (done through [WayBack]Arithmetic Expansion) and comparisons (through[WayBack] Other Comparison Operators).

The IEC suffixes contain one extra i to indicate binary and – next to the ISO notation that were already ISO defined – made it into the ISO 80000 standard since 2008. Here is a comparison list from [WayBackBinary prefix – Wikipedia:

Prefixes for multiples of
bits (bit) or bytes (B)
Decimal
Value SI
1000 k kilo
10002 M mega
10003 G giga
10004 T tera
10005 P peta
10006 E exa
10007 Z zetta
10008 Y yotta
Binary
Value IEC JEDEC
1024 Ki kibi K kilo
10242 Mi mebi M mega
10243 Gi gibi G giga
10244 Ti tebi
10245 Pi pebi
10246 Ei exbi
10247 Zi zebi
10248 Yi yobi

Most tools nowadays default to binary IEC suffixes for byte sizes, though disk manufacturers still use SI suffixes because, well then they appear bigger but aren’t. Just for comparison, look at the numbers from [WayBack] File size – Wikipedia and [WayBack] IEC and SI Size Notations – AN!Wiki where I got the test cases from:

Read the rest of this entry »

Posted in *nix, *nix-tools, bash, bash, Development, Power User, Scripting, Software Development | Leave a Comment »

sql server – I need a slow query on AdventureWorks (SQL 2005) – Stack Overflow

Posted by jpluimers on 2019/11/28

[WayBack] sql server – I need a slow query on AdventureWorks (SQL 2005) – Stack Overflow:

Medium slow:

SELECT * FROM Sales.SalesOrderDetail s
INNER JOIN Production.Product p ON s.ProductID = p.ProductID

Very slow:

SELECT * FROM Production.TransactionHistory th
INNER JOIN Production.TransactionHistoryArchive tha ON th.Quantity = tha.Quantity

It is based on the output of [WayBack] sql server – Query to list number of records in each table in a database – Stack Overflow, which originally ommited tables starting with dt (as those were be used for the “Database Diagram” in the SQL Server 7/2000 era using tables like dtProperties), but which I adopted using:

The query below does not support SQL Server 2000, where you would have to use things like objectproperty, but since by now even the [WayBack] documentation has been retired on the Microsoft site, you need to read [WayBack] Get list of tables but not include system tables (SQL Server 2K)? – Stack Overflow

In the end, it filters out tables like dbo.sysdiagrams that are generated by SQL Server Management Studio (SSMS), which are SSMS System Tables, but technically not SQL Server System Tables.

select
    s.name as SchemaName,
    t.name as TableName,
    i.name as indexName,
    p.rows,
    sum(a.total_pages) as TotalPages, 
    sum(a.used_pages) as UsedPages, 
    sum(a.data_pages) as DataPages,
    (sum(a.total_pages) * 8) / 1024 as TotalSpaceMB, 
    (sum(a.used_pages) * 8) / 1024 as UsedSpaceMB, 
    (sum(a.data_pages) * 8) / 1024 as DataSpaceMB
from 
    sys.tables t
inner join
    sys.schemas s on t.schema_id = s.schema_id
inner join
    sys.indexes i on t.object_id = i.object_id
inner join
    sys.partitions p on i.object_id = p.object_id and i.index_id = p.index_id
inner join
    sys.allocation_units a on p.partition_id = a.container_id
where
    t.is_ms_shipped = 0 -- not internal to SQL Server
    and
    (not exists (
        select ep.major_id
        from sys.extended_properties ep
        where 
            ep.major_id = t.object_id and
            ep.minor_id = 0 and
            ep.class = 1 and
            ep.name = N'microsoft_database_tools_support'
        )
    ) -- not internal to SQL Server Management Studio
    and
    i.index_id <= 1
group by
    s.name, t.name, i.object_id, i.index_id, i.name, p.rows
order by
    s.name, t.name

The counts for the [WayBack] GitHub version of AdventureWorks is this:

Read the rest of this entry »

Posted in Database Development, Development, Software Development, SQL Server | Leave a Comment »

delphi – Spring4D: Why is list of type TObjectList freed automatically after iteration? – Stack Overflow

Posted by jpluimers on 2019/11/28

A nice question and even nicer answer at [WayBack] delphi – Why is list of type TObjectList freed automatically after iteration? – Stack Overflow.

It comes down to the Spring4D collection classes expecting to be accessed using interface references because they descend from TInterfacedObject which also favours interface references over object references.

If you access them solely using object references, they start out with a reference count of 0 (zero). If an operation then first increases that to 1 (one), then decreases it back to 0 (zero), the collection instance gets freed.

A few nice tips and (sometimes opposing) opinions from the question/answer thread and the referencing G+ thread [WayBack] What do you think, +Stefan Glienke? ##Spring4D – Agustin Ortu – Google+ make them well worth reading.

Some:

  • Instead of TObjectList<TFuu>.Create, you should use TCollections.CreateObjectList<TFuu>.
    This way, you only need Spring.Collections in your uses clause
  • interface-only usage should be enforced by hiding the classes in the implementation, exposing only interfaces
  • The functions of TCollections only return interface references and – more importantly – allow for code folding starting with Spring4D 1.2.
  • Hiding the classes in an implementation part is not possible because then this would break any possibility to inherit from these classes and extend them (as I know people do).
  • Never use object references to classes that inherit from TInterfacedObject because the reference counting can kick in and destroy your instance anywhere (or manually call _AddRef/_Release).
  • if you want to have classes, then use System.Generics.Collections

–jeroen

Posted in Conference Topics, Conferences, Delphi, Development, Event, Software Development | Leave a Comment »

Git: Push a new or existing repo to Github · GitHub

Posted by jpluimers on 2019/11/27

Since I tend to forget the exact statements for starting a fresh repository and push it to a git hoster like GitHub or GitLab: [WayBack] Git: Push a new or existing repo to Github · GitHub

–jeroen

Posted in Development, DVCS - Distributed Version Control, git, GitHub, GitLab, Software Development, Source Code Management | Leave a Comment »

Delphi: IOTASourceEditor uses UTF8, so conversions are needed to/from regular strings

Posted by jpluimers on 2019/11/27

Some important points from [WayBackGo straight to JAIL! DO NOT Pass GO! DO NOT Collect £200 – Dave’s Development Blog.

The most important one is that the IOTASourceEditor (which is hardly documented in the docwiki) uses UTF8, so conversions are needed to/from regular strings.

The other is that by now any Unicode letter can be used as part of an Object Pascal identifiers so if you match, you need to take that into account.

Note that in practice using non-ASCII Unicode letters still fails with a lot of tooling (not just limited to Object Pascal), so be careful with those.

–jeroen

via: [WayBack] Go straight to JAIL! DO NOT Pass GO! DO NOT Collect £200  – David Hoyle – Google+

Posted in Delphi, Development, Software Development | Leave a Comment »

How to Send Emails with Gmail using Python

Posted by jpluimers on 2019/11/27

The cool thing about [WayBack] How to Send Emails with Gmail using Python is that it covers a broad range of email sending topics:

  • regular connections
  • secure connections
  • authenticating
  • rate limits
  • Google disallowing SMTP by default

Well wordt reading it, and the references:

–jeroen

Posted in Development, Python, Scripting, Software Development | Leave a Comment »

some links on bash and optional parameters

Posted by jpluimers on 2019/11/26

Hopefully I’ve been able to integrate some of the ideas in the links below in github.com/jpluimers/btrfs-du/blob/master/btrfs-du

One of the features I wanted there was to be able to add optional switches like --raw, --iec or --si to it similar to what as the btrfs qgroup show subcommand has.

It seems possible with bash, but it is not trivial, at least not for me as a non-frequent bash user, so here are some links to get me started:

In retrospect, other languages than bash might have been a better choice for a script like that (:

–jeroen

PS, some btrfs references:

Posted in *nix, *nix-tools, bash, bash, Development, Power User, Scripting, Software Development | Leave a Comment »

GitHub – NickRing/Delphi-Shortcut-Finder: Shows/find keyboard short-cuts have be assigned, that may be conflicting.

Posted by jpluimers on 2019/11/26

Cool tool: [WayBackGitHub – NickRing/Delphi-Shortcut-Finder: Shows/find keyboard short-cuts have be assigned, that may be conflicting.

Via: [WayBack] I need some help from anyone who knows RTTI better than me. I’m writing an OTA tool to list all the actions or keybindings that are associated with a s… – David Hoyle – Google+

David has an excellent series of blog posts on writing experts around his tool [WayBack] IDE Explorer – Dave’s Development Blog.

–jeroen

Posted in Delphi, Development, Software Development | Leave a Comment »

Unorthodocs: Abandon your DVCS and Return to Sanity – bitquabit

Posted by jpluimers on 2019/11/21

Some interesting thoughts on DVCS: [WayBackUnorthodocs: Abandon your DVCS and Return to Sanity – bitquabit

Besides the very good point it raises about DVCS (Git, Mercurial and most other DVCSes treat the whole state of the repository as the atom) it also indicates quite a few shortcomings:

  • most people hardly ever need the full history to be off-line
  • having the full history means repositories get huge in size, including your off-line clone
  • pseudo-solutions for huge repository sizes – like git-LFS or git-annex – are a no-go because now you loose atomicity
  • huge repositories in file or commit counts make them slow, especially when the trees are deep
  • splitting up repositories isn’t a good idea either because again: you loose atomicity
  • all DVCS are hard, not just git, because they are distributed and full of features
  • the workflow for submitting pull requests is quite a bit longer than submitting a patch, even though merging in a DVCS can be hard too (despite atomicity which does help a lot for DVCS systems)

I see many other advantages of DVCS systems (for instance that you only need to locally have the branches you are interested in, way better tooling for DVCS systems, ditto for sites hosting DVCS), but it always a good thing to know the weak spots of what you are working with.

–jeroen

Posted in Development, DVCS - Distributed Version Control, git, Mercurial/Hg, Software Development, Source Code Management | Leave a Comment »