Шаблоны проектирования Часть вторая

Порождающие шаблоны — Factory ( фабрика, фабричный метод) — Abstract Factory (абстрактная фабрика) — Singleton ( одиночка) — Lazy Load ( загрузка по требованию)

— Factory ( фабрика, фабричный метод)

— Abstract Factory (абстрактная фабрика)

— Singleton ( одиночка)

— Lazy Load ( загрузка по требованию)

Façade (фасад)

Façade (фасад) class TreeNode { } class SearchResult { } static class ACAlgoritm { public static TreeNode BuildTree(string[] a_Keywords) { … } public static SearchResult[] FindAll(TreeNode a_Root, string a_Text) { … } } class SearchAlgoritm { TreeNode m_Root; public SearchAlgoritm(string[] a_Keywords) { m_Root = ACAlgoritm.BuildTree(a_Keywords); } public SearchResult[] FindAll(string a_Text) { return ACAlgoritm.FindAll(m_Root, a_Text); } public static SearchResult[] FindAll( string[] a_Keywords, string a_Text) { return ACAlgoritm.FindAll( ACAlgoritm.BuildTree(a_Keywords), a_Text); } }

class TreeNode

{

}

class SearchResult

{

}

static class ACAlgoritm

{

public static TreeNode BuildTree(string[] a_Keywords)

{

…

}

public static SearchResult[] FindAll(TreeNode a_Root, string a_Text)

{

…

}

}

class SearchAlgoritm

{

TreeNode m_Root;

public SearchAlgoritm(string[] a_Keywords)

{

m_Root = ACAlgoritm.BuildTree(a_Keywords);

}

public SearchResult[] FindAll(string a_Text)

{

return ACAlgoritm.FindAll(m_Root, a_Text);

}

public static SearchResult[] FindAll(

string[] a_Keywords, string a_Text)

{

return ACAlgoritm.FindAll(

ACAlgoritm.BuildTree(a_Keywords), a_Text);

}

}

Façade (фасад) — Предоставить более удобный интерфейс для использования библиотеки, за счет наличия специальных удобных методов — Повысить читаемость клиентского кода (повышение уровня абстракции) — Снизить связанность между клиентским кодом и кодом модуля — Создать собственный хорошо спроектированный API для сторонней библиотеки, у которой свой API плохо спроектирован

— Предоставить более удобный интерфейс для использования библиотеки, за счет наличия специальных удобных методов

— Повысить читаемость клиентского кода (повышение уровня абстракции)

— Снизить связанность между клиентским кодом и кодом модуля

— Создать собственный хорошо спроектированный API для сторонней библиотеки, у которой свой API плохо спроектирован

Composite ( компоновщик)

Composite ( компоновщик) select * from Companies where (IsClient = 1 or IsFormerClient = 1) and IsDeleted = 0 and id_Object = 103

select * from Companies

where (IsClient = 1 or IsFormerClient = 1) and IsDeleted = 0 and id_Object = 103

Composite ( компоновщик) IsClient = 1 or IsFormerClient = 1) and IsDeleted = 0 and id_Object = 103

IsClient = 1 or IsFormerClient = 1) and IsDeleted = 0 and id_Object = 103

Composite ( компоновщик) interface IFilter { string GetSql(); } interface ICompositeFilter : IFilter { void AddFilter(IFilter a_Filter); }

interface IFilter

{

string GetSql();

}

interface ICompositeFilter : IFilter

{

void AddFilter(IFilter a_Filter);

}

Composite ( компоновщик) class ScalarFilter : IFilter { string m_Sql; public ScalarFilter(string a_Field, string a_Relation, object a_Value) { m_Sql = string.Format("{0} {1} {2}", a_Field, a_Relation, a_Value); } public ScalarFilter(string a_Field, object a_Value) : this (a_Field, "=", a_Value) {} public string GetSql() { return m_Sql; } }

class ScalarFilter : IFilter

{

string m_Sql;

public ScalarFilter(string a_Field, string a_Relation, object a_Value)

{

m_Sql = string.Format("{0} {1} {2}", a_Field, a_Relation, a_Value);

}

public ScalarFilter(string a_Field, object a_Value)

: this (a_Field, "=", a_Value) {}

public string GetSql()

{

return m_Sql;

}

}

Composite ( компоновщик) class AndFilter : ICompositeFilter { List<IFilter> m_Filters = new List<IFilter>(); public void AddFilter(IFilter a_Filter) { m_Filters.Add(a_Filter); } public string GetSql() { string result = string.Empty; foreach (IFilter filter in m_Filters) { if (result != &quot;&quot;) result += &quot; and &quot;; result += filter.GetSql(); } return result; } }

class AndFilter : ICompositeFilter

{

List<IFilter> m_Filters = new List<IFilter>();

public void AddFilter(IFilter a_Filter)

{

m_Filters.Add(a_Filter);

}

public string GetSql()

{

string result = string.Empty;

foreach (IFilter filter in m_Filters)

{

if (result != &quot;&quot;)

result += &quot; and &quot;;

result += filter.GetSql();

}

return result;

}

}

Composite ( компоновщик) protected IFilter GetFilterInternal() { XAndFilter result = new XAndFilter(); if (ObjectsItemSelection.HasSelectedItems) { XOrFilter objectFilter = new XOrFilter(); foreach (XObject obj in ObjectsItemSelection.SelectedItems) objectFilter.Add(new XScalarFilter(&quot;id_Object&quot;, obj.Id)); result.Add(objectFilter); } if (OperatorCheckBox.Checked || ClientCheckBox.Checked || FormerClientCheckBox.Checked) { XAndFilter categoryFilter = new XAndFilter(); if (OperatorCheckBox.Checked) categoryFilter.Add(new XScalarFilter(&quot;IsOperator&quot;, 1)); if (ClientCheckBox.Checked) categoryFilter.Add(new XScalarFilter(&quot;IsClient&quot;, 1)); … result.Add(categoryFilter); } if (HoldingComboBox.Text.Trim() != &quot;&quot;) { result.Add(DB.Companies.HoldingFilter(HoldingComboBox.Text.Trim())); } … return result; }

protected IFilter GetFilterInternal()

{

XAndFilter result = new XAndFilter();

if (ObjectsItemSelection.HasSelectedItems)

{

XOrFilter objectFilter = new XOrFilter();

foreach (XObject obj in ObjectsItemSelection.SelectedItems)

objectFilter.Add(new XScalarFilter(&quot;id_Object&quot;, obj.Id));

result.Add(objectFilter);

}

if (OperatorCheckBox.Checked || ClientCheckBox.Checked || FormerClientCheckBox.Checked)

{

XAndFilter categoryFilter = new XAndFilter();

if (OperatorCheckBox.Checked)

categoryFilter.Add(new XScalarFilter(&quot;IsOperator&quot;, 1));

if (ClientCheckBox.Checked)

categoryFilter.Add(new XScalarFilter(&quot;IsClient&quot;, 1));

…

result.Add(categoryFilter);

}

if (HoldingComboBox.Text.Trim() != &quot;&quot;)

{

result.Add(DB.Companies.HoldingFilter(HoldingComboBox.Text.Trim()));

}

…

return result;

}

Composite ( компоновщик) Компоновщик — это круто!

Компоновщик — это круто!

Ахтунг! public class XScalarFilter : IFilter { string m_Command; IDataParameter m_Parameter; public XScalarFilter(string a_Field, string a_Relation, object a_Value) { int counter = XFilter.Counter; m_Command = string.Format(&quot;{0} {1} @p{2}&quot;, a_Field, a_Relation, counter); m_Parameter = new SqlParameter(); m_Parameter.Value = a_Value; m_Parameter.ParameterName = &quot;@p&quot; + counter; } public XScalarFilter(string a_Field, object a_Value) : this(a_Field, &quot;=&quot;, a_Value) {} public string SqlText { get { return m_Command; } } public IList<IDataParameter> Parameters { get { return new IDataParameter[] { m_Parameter }; } } }

public class XScalarFilter : IFilter

{

string m_Command;

IDataParameter m_Parameter;

public XScalarFilter(string a_Field, string a_Relation, object a_Value)

{

int counter = XFilter.Counter;

m_Command = string.Format(&quot;{0} {1} @p{2}&quot;, a_Field, a_Relation, counter);

m_Parameter = new SqlParameter();

m_Parameter.Value = a_Value;

m_Parameter.ParameterName = &quot;@p&quot; + counter;

}

public XScalarFilter(string a_Field, object a_Value)

: this(a_Field, &quot;=&quot;, a_Value) {}

public string SqlText

{

get { return m_Command; }

}

public IList<IDataParameter> Parameters

{

get { return new IDataParameter[] { m_Parameter }; }

}

}

Задача

Command ( команда) interface ICommand { void Run(); } interface ICommand { void Do(); void UnDo(); } foreach(ICommand command in GetCommands()) { command.Do(); }

interface ICommand

{

void Run();

}

interface ICommand

{

void Do();

void UnDo();

}

foreach(ICommand command in GetCommands())

{

command.Do();

}

Command ( команда) <?xml version='1.0' encoding='windows-1251'?> <template> <parts> <part type=&quot;Cell&quot; cell=&quot;Contract&quot;> <sql>select ContractNumber from CompanyClients where id_Company = @id_Company</sql> </part> <part type=&quot;Cell&quot; cell=&quot;CompName&quot;> <sql>select FullName from Companies where id = @id_Company</sql> </part> <part type=&quot;Cell&quot; cell=&quot;SmallCompName&quot;> <sql>select FullName from Companies where id = @id_Company</sql> </part> <part type=&quot;Cell&quot; cell=&quot;Month&quot;> <sql>select @DateFrom</sql> </part> <part type=&quot;Table&quot; cell=&quot;AbonTable&quot; groupBy=&quot;BService&quot;> <sql> select ... </sql> </part> </parts> </template>

<?xml version='1.0' encoding='windows-1251'?>

<template>

<parts>

<part type=&quot;Cell&quot; cell=&quot;Contract&quot;>

<sql>select ContractNumber from CompanyClients where id_Company = @id_Company</sql>

</part>

<part type=&quot;Cell&quot; cell=&quot;CompName&quot;>

<sql>select FullName from Companies where id = @id_Company</sql>

</part>

<part type=&quot;Cell&quot; cell=&quot;SmallCompName&quot;>

<sql>select FullName from Companies where id = @id_Company</sql>

</part>

<part type=&quot;Cell&quot; cell=&quot;Month&quot;>

<sql>select @DateFrom</sql>

</part>

<part type=&quot;Table&quot; cell=&quot;AbonTable&quot; groupBy=&quot;BService&quot;>

<sql>

select ...

</sql>

</part>

</parts>

</template>

Command ( команда)

Плагины [TemplateItem(TemplateKind.ExcelSpreadsheet, &quot;Cell&quot;)] public class XCellTemplateItem : XTemplateItem { public override void Apply() { XExcelWorkDesk wd = (XExcelWorkDesk)WorkDesk; … } } [TemplateItem(TemplateKind.ExcelSpreadsheet, &quot;Table&quot;)] class XTableTemplateItem : XTemplateItem { }

[TemplateItem(TemplateKind.ExcelSpreadsheet, &quot;Cell&quot;)]

public class XCellTemplateItem : XTemplateItem

{

public override void Apply()

{

XExcelWorkDesk wd = (XExcelWorkDesk)WorkDesk;

…

}

}

[TemplateItem(TemplateKind.ExcelSpreadsheet, &quot;Table&quot;)]

class XTableTemplateItem : XTemplateItem

{

}

Плагины Type FindTypeByName(string a_Name) { foreach (Type type in GetType().Assembly.GetTypes()) { if (!type.IsSubclassOf(typeof(XTemplateItem))) { continue; } if (!type.IsDefined(typeof(TemplateItemAttribute), false)) { continue; } TemplateItemAttribute attr = (TemplateItemAttribute)type.GetCustomAttributes(typeof(TemplateItemAttribute), false)[0]; if (attr.TemplateKind == m_Template.TemplateKind && attr.Name == a_Name) { return type; } } return null; }

Type FindTypeByName(string a_Name)

{

foreach (Type type in GetType().Assembly.GetTypes())

{

if (!type.IsSubclassOf(typeof(XTemplateItem)))

{

continue;

}

if (!type.IsDefined(typeof(TemplateItemAttribute), false))

{

continue;

}

TemplateItemAttribute attr = (TemplateItemAttribute)type.GetCustomAttributes(typeof(TemplateItemAttribute), false)[0];

if (attr.TemplateKind == m_Template.TemplateKind && attr.Name == a_Name)

{

return type;

}

}

return null;

}

Template Method ( шаблонный метод) abstract class Game { protected int playersCount; protected abstract void initializeGame(); protected abstract void makePlay(int player); protected abstract bool endOfGame(); protected abstract void printWinner(); /* A template method : */ public void playOneGame(int playersCount) { this.playersCount = playersCount; initializeGame(); int j = 0; while (!endOfGame()) { makePlay(j); j = (j + 1) % playersCount; } printWinner(); } }

abstract class Game

{

protected int playersCount;

protected abstract void initializeGame();

protected abstract void makePlay(int player);

protected abstract bool endOfGame();

protected abstract void printWinner();

/* A template method : */

public void playOneGame(int playersCount) {

this.playersCount = playersCount;

initializeGame();

int j = 0;

while (!endOfGame()) {

makePlay(j);

j = (j + 1) % playersCount;

}

printWinner();

}

}

Template Method ( шаблонный метод) abstract public class XParser { public XCallInformation ParseAndProcess(XBillingString a_BillingString) { a_BillingString.SetParser(this); XCallInformation result = DoParse(a_BillingString); if (result == null) { XBilling.RegisterError(a_BillingString); } return result; } public XCallInformation Parse(XBillingString a_BillingString) { a_BillingString.SetParser(this); return DoParse(a_BillingString); } }

abstract public class XParser

{

public XCallInformation ParseAndProcess(XBillingString a_BillingString)

{

a_BillingString.SetParser(this);

XCallInformation result = DoParse(a_BillingString);

if (result == null)

{

XBilling.RegisterError(a_BillingString);

}

return result;

}

public XCallInformation Parse(XBillingString a_BillingString)

{

a_BillingString.SetParser(this);

return DoParse(a_BillingString);

}

}

Strategy ( стратегия) class XDocumentConflictManager { public XDocumentConflict FindConflict( XDocument a_Document, bool a_ForRegisteration) { XDocumentConflictFindingStrategy strategy = XDocumentConflictFindingStrategy.Create(a_Document, a_ForRegisteration); return new XDocumentConflict( a_Document, strategy.FindSameDocuments(), strategy); } }

class XDocumentConflictManager

{

public XDocumentConflict FindConflict(

XDocument a_Document, bool a_ForRegisteration)

{

XDocumentConflictFindingStrategy strategy = XDocumentConflictFindingStrategy.Create(a_Document, a_ForRegisteration);

return new XDocumentConflict(

a_Document,

strategy.FindSameDocuments(),

strategy);

}

}

Strategy ( стратегия) public abstract class XDocumentConflictFindingStrategy { XDocument m_Document; protected XDocumentConflictFindingStrategy(XDocument a_Document) { m_Document = a_Document; } public static XDocumentConflictFindingStrategy Create(XDocument a_Document, bool a_ForRegistration) { … } public IList<XDocument> FindSameDocuments() { return XDocumentRepository.Instance.Find(GetSameDocumentsFilter()); } protected abstract IFilter GetSameDocumentsFilter(); public abstract string GetConflictDefinition(); }

public abstract class XDocumentConflictFindingStrategy

{

XDocument m_Document;

protected XDocumentConflictFindingStrategy(XDocument a_Document)

{

m_Document = a_Document;

}

public static XDocumentConflictFindingStrategy Create(XDocument a_Document, bool a_ForRegistration)

{

…

}

public IList<XDocument> FindSameDocuments()

{

return XDocumentRepository.Instance.Find(GetSameDocumentsFilter());

}

protected abstract IFilter GetSameDocumentsFilter();

public abstract string GetConflictDefinition();

}

Strategy ( стратегия) public class XBillingConflictFindingStrategy : XDocumentConflictFindingStrategy { internal XBillingConflictFindingStrategy(XDocument a_Document) : base(a_Document) { } protected override IFilter GetSameDocumentsFilter() { return new XAndFilter( DB.vDocuments.idFilter(&quot;!=&quot;, Document.Id), DB.vDocuments.id_CompanyFilter(Document.Company.Id), DB.vDocuments.DocumentDateFilter(Document.DocumentDate), DB.vDocuments.id_TemplateFilter(Document.Template.Id) ); } public override string GetConflictDefinition() { return string.Format(&quot;Компания «{0}» уже имеет расшифровку «{1}» за «{2:MMMM yyyy}».&quot;, Document.Company.Alias, Document.Template.Name, Document.DocumentDate); } }

public class XBillingConflictFindingStrategy : XDocumentConflictFindingStrategy

{

internal XBillingConflictFindingStrategy(XDocument a_Document)

: base(a_Document)

{

}

protected override IFilter GetSameDocumentsFilter()

{

return new XAndFilter(

DB.vDocuments.idFilter(&quot;!=&quot;, Document.Id),

DB.vDocuments.id_CompanyFilter(Document.Company.Id),

DB.vDocuments.DocumentDateFilter(Document.DocumentDate),

DB.vDocuments.id_TemplateFilter(Document.Template.Id)

);

}

public override string GetConflictDefinition()

{

return string.Format(&quot;Компания «{0}» уже имеет расшифровку «{1}» за «{2:MMMM yyyy}».&quot;,

Document.Company.Alias, Document.Template.Name, Document.DocumentDate);

}

}